The Laws of Simplicity by John Maeda

• Simplicity = Sanity
• Simplicity is a quality that not only evokes passionate loyalty for a product design, but also has become a key strategic tool for businesses to confront their own intrinsic complexities.
• There are three flavors of simplicity discussed here, where the successive set of three Laws correspond to increasingly complicated conditions of simplicity: basic, intermediate, and deep.
• Ten Laws
• Reduce: The simplest way to achieve simplicity is through thoughtful reduction.
• Organize: Organization makes a system of many appear fewer.
• Time: Savings in time feel like simplicity.
• Learn: Knowledge makes everything simpler.
• Differences: Simplicity and complexity need each other.
• Context: What lies in the periphery of simplicity is definitely not peripheral.
• Emotions: More emotions are better than less.
• Trust: In simplicity we trust.
• Failure: Some things can never be made simple.
• The One: Simplicity is about subtracting the obvious, and adding the meaningful.
• Three Keys
• Away: More appears less by simply moving it far, far away.
• Open: Openness simplifies complexity.
• Power: Use less, gain more.
• The easiest way to simplify a system is to remove functionality.
• The simplest way to achieve simplicity is through thoughtful reduction.
• When it is possible to reduce a system’s functionality without significant penalty, true simplification is realized.
• Making things smaller doesn’t make them necessarily better, but when made so we tend to have a more forgiving attitude towards their existence. A larger-than-human-scale object demands its rightful respect, whereas a tiny object can be something that deserves our pity.
• Any design that incorporates lightness and thinness conveys the impression of being smaller, lesser, and humbler. Pity gives way to respect when more value is delivered than originally expected.
• Hide the complexity through brute-force methods. A classical example of this technique is the Swiss army knife. Only the tool you wish to use is exposed, while the other blades and drivers are hidden.
• The computer has an infinite amount of capacity to hide in order to create the illusion of simplicity.
• Shrinking an object lowers expectations, and the hiding of complexities allows the owner near to manage the expectations himself.
• Technology creates the problem of complexity, but also affords new materials and methods for the design of our relationship with complexities that shall only continue to multiply.
• Consumers will only be drawn to the smaller, less functional product if they perceive it to be more valuable than a bigger version of the product with more features. Thus the perception of quality becomes a critical factor when making the choice off less over more.
• Perceived excellence can be programmed into consumers with the power of marketing.
• Embodying an object with properties of real quality is the basis of the luxury goods industry and iis rooted in their use of precious metals and exquisite craftsmanship.
• The upside of materializm is that the way something we own feels can change how we feel.
• The home is usually the first battleground ttt that comes to mind when facing the daily challenge of managing complexity. Stuff just seems to multiply. There are three strategies for achieving simplicity in the living realm:
• Buy a bigger house
• Put everything you don’t really need into storage
• Organize your existing assets in a systematic fashion
• Organization makes a system of many appear fewer. Of course this will only hold if the number of groups is significantly less than the number of items to be organized.
• The Pareto Principle is useful as a rule of thumb: assume that in any given bin of data, generally 80% can be managed at lower priority and 2000% requires the highest level.
• Everything is important, but knowing where to start is the critical first step.
• Finding the organizational scheme that works best for you is a wise investment.
• The tabular from of viewing data is by no means rocket science, but it is a rare sort of visual magic that always works. In the medium of text, tabs break up the linear space of a document such that the paragraphs can stand out as the organizing principle.
• Humans are organization animals. We can’t help but to group and categorize what we see.
• The principles of Gestalt to seek the most appropriate conceptual “fit” are important not only for survival, but lie at the very heart of the discipline of design.
• Groups are good; too many groups are bad because they counteract the goal of grouping in the first place.
• Blurred groupings are powerful because they can appear even more simple, but at the cost of becoming more abstract, less concrete. Hence simplicity can be a creative way of looking at the world that is driven by design.
• When forced to wait, life seems unnecessarily complex. Savings in time feel like simplicity. And we are thankfully loyal when it happens, which is rare.
• Reducing the time spent waiting translates into time we can spend on something else. In the end it’s about choosing how we spend the time we’re given in life.
• Reducing a five-minute task to one minute is the raison d’etre of operations management, the field that has brought us a world that never sleeps and is always on time.
• Giving up the option of choice, and letting a machine choose for you, is a radical approach to shrinking the time we might spend otherwise fumbling with the iPod’s scroll-wheel.
• At the end of the day, there is an end of the day. Thus choosing when to care less versus when to care more lies at the heart of living an efficient but fulfilling daily life.
• Telling people how much time they have left to wait is a humane practice that is becoming more popular.
• Knowledge is comfort, and comfort lies at the heart of simplicity.
• Making critical processes run faster is a fantastic benefit to humankind.
• The realization that life is about waiting comes later in life. As a child, the idea of waiting is something foreign and simply intolerable. But waiting is what we do in the adult world. We do it all the time.
• When speeding-up a process is not an option, giving extra care to a customer makes the experience of waiting more tolerable.
• Saving time or staying in step with the flow of time--whichever costs the least to implement--will usually win the day.
• Saving time is thus the tradeoff between the quantitatively fast versus the qualitatively fast.
• Knowledge makes everything simpler. This is true for any object, no matter how difficult.
• The problem with taking time to learn a task is that you often feel you are wasting time, a violation of the third Law.
• Being a professor is the easiest thing in the world--you just have to act like you know all the answers. Being a student is much harder because you not only have to wring the answers from the cryptic professor, but you also have to make sense of them.
• Learning occurs best when there is a desire to attain specific knowledge.
• The first step in conveying the basics is to assume the position of the first-time learner.
• Observing what filas to make sense to the non-expert, and then following that trail successively to the very end of the knowledge chain is the critical path to success.
• The easiest way to learn the basics is to teach the basics yourself.
• Repeating yourself can be embarrassing, especially if you are self-conscious--which most everyone is. But there’s no need to feel ashamed, because repetition works and everyone does it.
• A gentle, inspired start is the best way to draw students, or even a new customer, into the immersive process of learning.
• Inspiration is the ultimate catalysts for learning: internal motivation trumps external reward.
• The practice of education is the highest form of intellectual philanthropy.
• The best designers marry function with form to create intuitive experiences that we understand immediately--no lessons (or cursing) needed. Good design relies to some extend on the ability to instill a sense of instant familiarity.
• Design starts by leveraging the human instinct to relate, followed by translating the relationship into a tangible object or service, and then ideally adding a little surprise at the end to make your audience’s efforts worthwhile. Or writing these steps in shorthand: relate-translate-surprise!
• Metaphors are useful platforms for transferring a large body of existing knowledge from one context to another with minimal, often imperceptible, effort on the part of the person crossing the conceptual bridge. But metaphors are only deeply engaging if they surprise along some unexpected, positive dimension.
• A metaphor used as a learning shortcut for a complex design is most effective when its execution is both relevant and delightfully unexpected.
• Difficult tasks seem easier when they are “need to know” rather than “nice to know”.
• In the beginning of life we strive for independence, and at the end of life it is the same. At the core of the best rewards is this fundamental desire for freedom in thinking, living, and being.
• We know how to appreciate something better when we can compare it to something else.
• Simplicity and complexity need each other. The more complexity there is in the market, the more that something simpler stands out. And because technology will only continue to grow in complexity, there is a clear economic benefit to adopting a strategy of simplicity that will help set your product apart. That said, establishing a feeling of simplicity in design requires making complexity consciously available in some explicit form.
• There is no way to connect with simplicity when how complexity feels has been forgotten.
• The opportunity lost by increasing the amount of blank space is gained back with enhanced attention on what remains. More white space means that less information is presented.
• When there is less, we appreciate everything much more.
• Simple objects are easier and less expensive to produce, and those savings can be translated directly to the consumer with desirable low prices.
• The combination of a simple object together with a host of optional accessories gives consumers the benefit of expressing their feelings and feelings for their objects.
• The best art makes your head spin with questions. Perhaps this is the fundamental distinction between pure art and pure design. White great art makes you wonder, great design makes things clear.
• A certain kind of more is always better than less--more care, more love, and more meaningful actions I don’t think I need to say anything more really.
• Vanity is a high risk sport that raises the stakes when all you can offer to a client is your word and your reputation as a Master. Overconfidence is usually the enemy of greatness, and there’s little room for personal ego when pleasing a customer is the true priority.
• Knowing that a purchase is correctable later makes the shopping process simpler because you know that any decision make is not final.
• A product that can correct our mistakes as they happen performs an important service and gains our trust.
• Trusting a power greater than our own is a custom that is ingrained from birth when the adults that care for us provide the ultimate experience of simplicity. Every need and desire is met by a parent; and in return, beyond just offering our trust, we entrust our love.
• In contrast to the trusting relationship with a Master, the power of undo results in a feeling of simplicity that is rooted in not having to care at all.
• Embrace undo as a rational partner in maintaining the many complex relationships with the objects in your environment.
• The more a system knows about you, the less you have to think. Conversely, the more you know about the system, the greater control you can exact.
• Some things can never be made simple.
• Knowing that simplicity can be elusive in certain cases is an opportunity to make more constructive use of your time in the future, instead of chasing after an apparently impossible goal. However there’s no harm in initiating the search for simplicity even when success is deemed as too closely or otherwise out of reach.
• Everyone’s instinct is different, and thus a single answer is not readily available to achieve the optimal balance between simplicity and complexity.
• Simplicity is hopelessly subtle, and many of its defining characteristics are implicit (noting that it hides in simplicity).
• Simplicity is about subtracting the obvious, and adding the meaningful.
• More appears like less by simply moving it far, far away. Thus an experience is made simpler by keeping the result local, and moving the actual work to a far away location.
• Fundamental to the effectiveness of away is how to maintain reliable communication with an outsourced task.
• Openness simplifies complexity. With an open system, the power of the many can outweigh the power of the few.
• A deep form of simplicity is rooted in trust.
• Electronic devices can never be truly simple unless the are freed from their dependence on power. A seemingly unpowered electronic device may seem like an oxymoron, but it is critical to achieve.
• The mercurial cost of fuel and it's inevitable link to geopolitics make any discussion of power complex.
• Technology and life only become complex if you let it be so.
• While technology is an exhilarating enabler, it can be an exasperating disabler as well.

The Warrior Ethos by Steven Pressfield

• The Warrior Ethos embodies certain virtues--courage, honor, loyalty, integrity, selflessness and others--that most warrior societies believe must be inculcated from birth.
• Every warrior virtue proceeds from this--courage, selflessness, love of and loyalty to one’s comrades, patience, self-command, the will to endure adversity. It all comes from the hunting band’s need to survive.
• In the ear before gunpowder, all killing was of necessity done from hand to hand.
• Some say that self-preservation is the strongest instinct of all, not only in humans but in all animal life.
• The Warrior Ethos evolved to counter the instinct of self-preservation.
• Against this natural impulse to flee from danger (specifically from an armed and organized human enemy), the Warrior Ethos enlists three other equally innate and powerful human impulses:
• Shame
• Honor
• And love
• Courage--in particular, stalwartness in the face of death--must be considered the foremost warrior virtue.
• No one is born with the Warrior Ethos, though many of its tenets appear naturally in young men and women of all cultures.
• The Warrior Ethos is taught.
• Courage is modeled for the youth by fathers and older brothers, by mentors and elders. It is inculcated, in almost all cultures, by a regimen of training and discipline. This discipline frequently culminates in an ordeal of initiation.
• Every honorable convention has its shadow version, a pseudo or evil-twin manifestation in which noble principles are practiced--but in a “dark side” system that turns means and ends on their heads.
• Tribes are tied to the land and draw strength from the land. Tribes fight at their best in defense of home soil.
• Sociologists tell us that there are two types of cultures: guilt-based and shame-based.
• Individuals in a guilt-based culture internalize their society's conceptions of right and wrong. The sinner feels his crime in his guts. He doesn’t need anyone to convict him and sentence him; he convicts and sentences himself.
• A shame-based culture is the opposite. IN a shame-based culture, “face” is everything. All that matters is what the community believes of us.
• Warrior cultures (and warrior leaders) enlist shame, not only as a counter to fear but as a goad to honor.
• The interesting thing about peoples and cultures from rugged environments is that they almost never choose to leave them.
• Better to live in a rugged land and rule than to cultivate rich plains and be a slave.
• The greatest counterpoise to fear, the ancients believed is love--the love of the individual warrior for his brothers in arms.
• Ordeals of initiation are undergone not as individuals but as teams, as units.
• Courage is inseparable from love and leads to what may arguably be the noblest of all warrior virtues: selflessness.
• The group comes before the individual. This tenet is central to the Warrior Ethos.
• Selflessness produces courage because it binds men together and proves to each individual that he is not alone. The act of open handedness evokes desire in the recipient to give back.
• Among all elite U.S. forces, the Marine Corps is unique in that its standards for strength, athleticism and physical hardiness are not exceptional. What separates Marines, instead, is their capacity to endure adversity. Marines take a perverse pride in having colder chow, crappier equipment and higher casualty rates than any other service.
• This is another key element of the Warrior Ethos: the willing and eager embracing of adversity.
• In warrior cultures--from the Sioux and the Comanche to the ulu and the mountain Pashtun--honor is a man’s most prized possession.
• Warrior cultures employ honor, along with shame, to produce courage and resolve in the hearts of their young men.
• Honor is the psychological salary of any elite unit. Pride is the possession of honor.
• The warrior sense of humor is terse, dry--and dark. Its purpose is to deflect fear and to reinforce unity and cohesion.
• For the warrior, all choices have consequences. His decisions have meaning; every act he takes is significant. What he says and does can save (or cost) his own life or the lives of his brothers.
• The American military is a warrior culture embedded within a civilian society.
• The greatness of American society, like its Athenian progenitor, is that it is a civilian society. Freedom and equality are the engines that produce wealth, power, culture and art and unleash the greatness of the human spirit.
• The returning warrior may not realize it, but he has acquired an MBA in enduring adversity and a Ph.D. in resourcefulness, tenacity and the capacity for hard work.
• The returning warrior possesses the Warrior Ethos, and this is a mighty ally in all spheres of endeavor.
• But the Warrior Ethos commands that brute aggression be tempered by self-restraint and guided by moral principle.
• When an action is unject, the warrior must not take it.
• The capacity for empathy and self-restrain will serve us powerfully, not only in our external wars but in the conflicts within our own hearts.
• Human history, anthropologists say, can be divided into three stages--savagery, barbarism, and civilization.
• The collective unconscious, Jung said, contains the stored wisdom of the human race, accumulated over thousands of generations.
• The collective unconscious is the software we’re born with. It’s our package of instincts and preverbal knowledge. Within this package, Jung discovered what he called the archetypes.
• Archetypes are the larger-than-life, mythic-scale personification of the stages that we pass through as we mature.
• Archetypes serve the purpose of guiding us as we grow. A new archetype kicks in at each stage. It makes the new phase “feel right” and “seem natural”.
• One of the primary archetypes is the Warrior. The warrior archetypes exists across all eras and nations and is virtually identical in every culture.
• The hardest thing in the world is to be ourselves.

Seeing Theory by Delvin, Guo, Kunin, Xiang

• Making predictions about something as seemingly mundane as tomorrow's weather, for example, is actually quite a difficult task.
• In general, it is important in statistics to understand the distinction between theoretical and empirical quantities.
• A probability is always a number between 0 and 1 inclusive.
• The sample space is the set of all possible outcomes in the experiment.
• Collections of outcomes in the sample space are called events.
• The sum of the probabilities of all the outcomes in a sample space must be 1.
• Once we know the probabilities of the outcomes in an experiment, we can compute the probability of any event.
• The probability of an event is the sum of the probabilities of the outcomes it comprises.
• The concept of average value is an important one in statistics.
• The variance of a random variable X is a non-negative number that summarizes on average how much X differs from its mean, or expectation.
• The square root of the variance is called the standard deviation.
• One of the main reasons we do statistics is to make inferences about a population given data from a subset of that population.
• A set is a collection of items, or elements, with no repeats.
• The number of permutations, or orderings, of n distinct objects is given by the factorial expression.
• A function X that maps outcomes in our sample space to real numbers is called a random variable.
• The word "countably" refers to a property of a set. We say a set is countable if we can describe a method to list out all of the elements in the set such that for any particular element in the set, if we wait long enough in our listing process, we will eventually get to that element. In contrast, a set is called uncountable if we cannot provide such a method.
• A random variable X is called discrete if X can only take on finitely many or countably many values.
• We say that X is a continuous random variable if X can take on uncountably many values.
• If X is a continuous random variable, then the probability that X takes on any particular value is 0.
• A continuous random variable is distributed according to a probability density function, usually denoted f, defined on the domain of X.
• There are two fundamental types of errors in hypothesis testing. They are denoted Type I and Type II error.
• A Type I error is made when we reject H0 when it is in fact true.
• A Type II error is made when we accept H0 when it is in fact false.
• The frequentist approach to inference holds that probabilities are intrinsically tied to frequencies.
• Bayesian inference takes a subjective approach and views probabilities as representing degrees of belief.
• The goal of Bayesian inference is to update our prior beliefs by taking into account data that we observe.
• Linear regression is one of the most widely used tools in statistics.
• In reality, most random variables are not actually independent.

How to Get Your Point Across in 30 Seconds--or Less by Milo O. Frank

• The future is a high-speed car without a driver. You have to be the driver. You have to plan. You had to decide the direction you’re going to take.
• Thirty seconds may not seem like a long time. But it’s long enough to say what you want to say.
• Thirty seconds can change the direction of your career and your life.
• Communicating effectively, persuasively, and concisely can be easily learned.
• Time waits for no man; you have to move faster just to stay even. And to move faster, you must be concise.
• The hour of years ago is the 30 seconds of today. To survive and move ahead in business or in any other relationship, you must be able to get your point across swiftly and succinctly in 30 seconds or less.
• The attention span of the average individual is 30 seconds.
• Don’t wait forever. It’s the things you don’t do that you regret.
• The objective is the goal, the destination, the purpose, the end in view, the target, the raison d’etre. It’s what you want to achieve. It’s why you’re there. It’s what you must have in order to take effective action. It’s the definitive reason for you to enter any serious business conversation or undertake any form of communication in which you have a point to make.
• It’s surprising how often opportunity is wasted because a person has an unclear or mixed objective.
• It’s been my experience that most people in business, and even leaders in industry and government, don’t really know what their objective is.
• Only by determining your objective precisely can you take the first vital step toward getting your point across.
• There may be times when it’s bad strategy to state your objective.
• Every form of business communication--whether it’s a job interview, a conversation between boss and employee, a memo, a presentation, a sales talk--should have a single clear-cut objective. Otherwise, you’re wasting your time and your listener’s time. And you should know what that objective is before you open your mouth or put pen to paper.
• Your objective is your goal, purpose, or destination. It is why you are there. You can have only one objective.
• In every form of business communication, your thoughts and words should introduce, reinforce, or help you achieve your objective.
• You do not have to state your objective except to yourself.
• The first basic principle of the 30 second message is to have a single clear-cut objective.
• Knowing your listener and what he wants is the second basic principle of the 30-second message.
• So once you’ve determined your objective, always ascertain who can give you what you want.
• Go to the person who can get it done.
• Knowing who you’re talking to can help guide you in planning to get what you want.
• In order to get your point across in 30 seconds or less, first determine your objective, and second, determine the right person or group of persons who can give you what you want. Then learn all you can about that person or group. Finally, and most important, know what that person or group is going to want from you.
• Go to the right person, the person who can give you what you want.
• Know as many facts as possible about their person or persons you’ll be talking to.
• Identify with your listener. What does he want from you, and what one thing more than any other will get a favorable reaction from him?
• Knowing your listeners and what they want is the second basic principle of the 30-second message.
• The third basic principle of a 30-second message is a well-formulated approach.
• The right approach is the single thought or sentence that will best lead you to your objective.
• The number of potential approaches to achieve an objective is unlimited. There are as many as your imagination will allow. But just as you should have only one clear-cut objective, so you must choose only one approach.
• The right approach without an objective is useless.
• Your knowledge of the needs and interests of your listener will also influence the approach you choose to take.
• A clear-cut right approach stated in a single sentence is a guarantee against ever forgetting what you’re talking about.
• Know what you want, know who can give it to you, and know how to get it: those are the essentials of every form of spoken or written communication.
• The right approach is the single thought or sentence that will best lead to your objective.
• The right approach will also take into consideration the needs and interests of your listener.
• The right approach will give you focus, and always keep you on track toward achieving your objective.
• Knowing what you want, who can give it to you and how to get it are the three basic principles of the 30-second message.
• A hook is a statement or an object used specifically to get attention.
• The first thing you must do when you talk to anyone--whether it’s your employee, your associate, your boss, or the chairman of the board--is get his attention.
• To find your hook for any 30-second message, answer the following questions:
• What’s the most unusual part of your subject? Can you reduce it to one sentence?
• What’s the most interesting and exciting part of your subject? Can you reduce it to one sentence?
• What’s the most dramatic part? Can you reduce it to one sentence?
• What’s the most humorous part? Can you reduce it to one sentence?
• A hook ican be serious, dramatic, or humorous, but it must capture interest. If it’s dull, it won’t accomplish its purpose, which is to get attention.
• The more dynamic the hook, the more effective the total message becomes.
• Humor, if used properly, is a powerful tool and a splendid hook.
• The best humorous hooks are anecdotes or personal experiences. And when you use them, you’re not limited to one sentence.
• Humorous anecdotes and personal experience are excellent hooks, as long as they relate directly to your objective and your listener, and lead you to the point you wish to get across.
• Sometimes the best hook is visual rather than verbal.
• Keep track of personal experiences and anecdotes that may make good hooks by jotting them down in a notebook.
• A hook is a statement or an object used specifically to get attention.
• To get your listener’s or reader’s attention, use a hook as the first statement in your 30-second message.
• Your hook should relate to your objective, your listener, and your approach.
• Your hook cna be a question ro a statement, and it can be dramatic or humorous. If it’s a question, it must be answered.
• Anecdotes or personal experiences make excellent hooks.
• Your entire message can be a hook.
• Keep a hook book.
• It always pays to remember the three K’s of communication:
• Katch ‘em.
• Keep ‘em.
• Konvince ‘me.
• The subject of your 30-second message must explain, reinforce, and prove the point you are there to make. In order to do this, the subject must contain all or any part of that famous formula: what, who, where, when, why, and how.
• How to develop your subject:
• Step 1
• Know your objective.
• Know your listener.
• Know your approach.
• Step 2
• What am I talking about?
• Who is involved?
• Where is it?
• When is it?
• Why is it?
• How do I do it?
• Step 3
• Do they reinforce and/or explain my objective?
• Do they relate to my listener?
• Do they correspond to my approach?
• You may have chosen the right approach to achieve your objective, you may have captured your listener's attention with a provocative hook, but your message will be lost unless you know your subject, and present it as concisely and forcefully as possible.
• The subject explains and reinforces your objective.
• The subject relates to your listener.
• The subject contains and corresponds to your approach.
• What, who, where, when, why, and how are all part of your subject.
• The subject is what your 30-second message is all about.
• Know your subject and present it as concisely and forcefully as possible.
• At the end of each 30-second message, you must ask for what you want.
• If you don’t ask for something specific, the chances are you’ll get nothing. It all comes down to one practicality: he who don’t ask, don’t get.
• To determine the close the best fits with the objective to your 30-second message, simply ask yourself,  “What do I want from my listener?”
• There are two types of close for a 30-second message: a demand for action and a demand for a reaction.
• An action close demands as specific action on the part of your listener, and that action should not merely be implied.
• If you ask someone to perform a specific action within a specific time frame, you’re more likely to get what you want.
• There are often times when it may be impossible to demand a specific action--or it just may not be good strategy. That’s the opportune moment for the soft sell or the reaction close which uses the power of suggestion of the power of example to get the desired results.
• Strategy is very important when it comes to choosing your close. The two operative rules are: Know your objective and Know your listener.
• Decide in advance what your strategy should be. But above all, don’t walk into a blind alley. Always leave a way out. You won’t get what you want if you don’t ask for it. But if you don’t know how to ask for it, you won’t get it either.
• A message without a specific request is a wasted opportunity.
• He who don't ask, don’t get.
• The action close calls for a specific action within a specific time frame.
• The reaction close is the strategy to use when your best chance is to ask indirectly.
• Decide your close in advance. Don’t foreclose opportunity.
• A truly effective 30-second message is more than a hook, a few words, and a close. Those words should paint a picture our listener will remember. They should be words your listener will understand. They should relate to your own and your listener's personal experiences. And they should teach your listener's heart.
• When you communicate, you want your listener to “see” as well as hear what you’re saying. Descriptive words help the listener visualize what you’re talking about.
• Imagery is useful in all types of daily communication.
• A major problem of communicating, particularly in the business world, is simply understanding what the other person is saying. People in different companies and industries often just don’t speak the same language. They speak business-ese. Even within the same company, I’ve seen a lack of understanding because of the “language” problem.
• The fastest way to put your listener to sleep is to talk to him in language he doesn’t understand.
• Choosing words and images appropriate to your listeners level of understanding is the one surefire way of getting your point across.
• One of the simplest and most natural ways to get rid of business-ese in your 30-second message is to personalize by using a personal story to illustrate your point. If your listener can identify with you and a personal experience you have had, ti will make your message much more effective.
• The most effective messages are those that reach the heart of the listener. Emotion causes change. If you can appeal to the emotions of your listener, he will become more receptive to your words.
• Imagery, clarity, personalizing, and emotional appeal will give power and memorability to your 30-second message.
• Imagery: Think in pictures and use descriptive words your listener will remember.
• Clarity: Use clear and simple language your listener will understand.
• Personalizing: To illustrate your point, use personal stories that your listener can identify with.
• Emotional appeal: Touch the heart of your listener. He will be more receptive to your 30-second message.
• It’s undeniably true that how you say something is often more important than what you say.
• First impressions are often the most lasting. And if that first impression is not a good impression, you will have lost an opportunity that may never come again.
• Nothing is more warming than a smile, when you mean it. And don’t kid yourself: if you force a smile, your listener will know it’s phony.
• To create a genuine smile, just think of something that amuses you. Better still, put some humor in your 30-second message. If you say something amusing with a smile, nine times out of ten your listener will smile right along with you.
• A smile before you begin your 30-second message and after you conclude it creates a good first--and last--impression. It’s a good way to introduce yourself to your listener--we all look more attractive when we smile--and a good way to thank him for his attention.
• Eye contact also conveys important nonverbal messages.
• Direct eye contact is an excellent way to emphasize a point and establish your own sincerity.
• Variety of expression is the key to keeping your listener's attention and interest.
• Your movements, gestures, and postures are just as revealing as your facial expressions.
• Your posture--how you carry yourself whether you’re standing or sitting--sends a double nonverbal message: it reveals what you think of yourself and what you think of your listener.
• If you slouch or shamble, it conveys indifference to how you look and to anyone who is looking at you.
• Self-awareness is the secret. When you are aware of how you look to others, you can use that knowledge to look the way you want to look.
• If you believe in what you’re saying, that will be reflected in your voice and your listener will believe it too.
• No one can deny that what you wear--and how you wear it--sends powerful signals.
• Our clothing and accessories are an indication of our status, who we think we are and what we want others to think of us.
• Styles and fashion are always changing, and the first rule about clothes, accessories, and hairstyle is that there are no rules. It’s up to you. If you’re comfortable with yourself, then you’ll be comfortable with whatever you wear. But trying to make yourself look younger or older than you are, or trying to look like someone you obviously are not, is the best way I know to make yourself and everyone else uncomfortable.
• It’s always a good idea to avoid extreme, unless you’re in the business of attracting attention to yourself.
• Your clothing and personal appearance speak for you before you’ve even said a word. It’s only common sense to send the signals you want to send. All the rest is static.
• When you care enough to present yourself at your best, then people will care about you. If you’re not really sure what makes you look your best, take the time and make the effort to find out, seeking advice from either friends or pressionales. That, too, shows you care.
• Your goals is spontaneity and sincerity. Your goals is to be yourself. The best way to achieve this is:
• Be prepared.
• Don’t memorize.
• Personalize.
• Care about what you are saying.
• If you don’t know what you look like when you’re speaking, practice in front of a mirror.
• Whenever you have a choice, stand. It will always be more effective, because you can gesture and move more easily when emphasizing the point you’re trying to make.
• The voice is an actor’s most important tool--and it can be yours too. Many people don’t know hot why look, and even more are unaware of how they sound.
• One of the best techniques for emphasizing an important sentence in your 30-second message is to speak the last few words softly.
• Another attention-getter is the pause. The pause is one of the most valuable speaking tools because it accomplishes so much. It gives emphasis to what you’re saying. It gives you time to think. It gives your listener an opportunity to hear, absorb, and retain what you’re saying. It also gives you a chance to see if your listener understands.
• Know your object, know your listener, and know your approach. Choose the words that will create the most favorable impression on your listener and help you achieve your objective. Then make sure the image you convey as you speak those words will help you achieve the same goal.
• First impressions may be the most lasting impressions. Make sure they are good impressions.
• How you deliver your 30-second message is often more important than what you say.
• If your facial expressions, especially your smile, are sincere and appropriate, they can make your 30-second message more effective.
• Your movements, gestures, and posture should attract your listener’s attention to your 30-second message, not distract it.
• In delivering your 30-seance message, strive for the qualities in your voice that make for good conversation--animation, enthusiasm, variety, informality, and sincerity.
• Your clothes and personal appearance send perful messages. Make sure they are the messages you want to send.
• Be yourself.
• Once you have organized your speech as a whole, look at its parts. There will probably be more than one point you want to get across. Consider each of them as an individual 30-second message.
• Never memorize! You cannot communicate with your audience if you’re struggling to remember each word of a speech.
• Master your material, but don’t memorize. Memorizing robs you of being natural.
• Never read a speech to an audience! There is a big difference between the written word and the spoken word. They are different forms of expression. A well planned, beautifully written speech may be powerful on paper, but when it’s read aloud it can become stilted and unnatural.
• You’re never there to give a speech. You’re there to communicate with your audience.
• Even the most experienced speakers are nervous. But once you get into your talk, your nerves will disappear.
• Variety is the spice of your speaking life. Without it, everything you say will be dull, boring, and ineffective. Also, you won’t be very popular with your listeners.
• Keep in mind that the attention span of an audience listening to a speech is also 30 seconds. That means if you wish to keep the interest and attention of your audience, you must do something different every 30 seconds.
• When you’re speaking to a group, establishing your credibility is a top priority. You want your audience to know why they should listen to you, and a few brief words about your credentials will help your credibility. Better yet, tell a personal anecdote that will relate directly to your audience’s experience and establish that fact that, even though you’re the chairman of the board, a famous astrophysicist, or an expert in the coronary bypass surgery, you’re human.
• Knowing how you’re going to end your speech will give you a target to aim at, a destination to work toward.
• Whether your audience is one or a thousand, the same basic principles and strategies of the 30-second message still apply.
• Don’t memorize.
• Don’t read.
• Outline your speech, write a rough draft, and then reduce it to notes on three-by-five cards.
• Rehearse your speech, but strive for spontaneity, variety, and naturalness, in both your words and your movements.
• Establish your credibility and describe your credentials in personal anecdotes.
• Write your own introduction.
• Know when to stop.
• The skillful speaker previews in his mind the point he wants to get across in response to any anticipated question. His knowledge of his objective, his listener, his approach, and his subject allows him to frame an answer that is direct, concise, informal, and effective. In short, the perfect answer.
• Know your objective, your listener, and your approach before you make the call.
• It never hurts to repeat [your] message as many times as necessary, as long as you rephrase it or elaborate upon it on slightly different ways every tim. Repetition is a standard technique in advertising.
• Business meetings are often inconclusive and boring because the participants are not well prepared. There is too much ground to cover, too many ideas and subjects to be discussed, too many choices to be made. You must narrow them down before the meeting so key points can be properly examined and logical decisions arrived at. The meeting should have a specific agenda, and it’s up to the person who is calling and conducting the meeting to prepare it.
• Keep your thank-you notes short, sweet, and sincere.
• A concise, 30-second message is the perfect answer to any question.
• Using the question turnabout, you can get your own point across in answer to any question.
• Know your objective, your listener, and your approach before you make any business phone call.
• If you can’t reach the person you’re calling, leave a message giving him a good reason to call back.
• Make all the key points in your sales pitch in 30-seconds--or less.
• A carefully prepared agenda, calling for concise, 30-second statements from participants on all key points, will save time in any business meeting.
• You can take any opportunity to deliver your 30-second message. You can even make your own opportunity, if you are prepared.
• All the rules and strategies of the 30-second messages can be applied to your written business communications.
• Written or spoken, the 30-second message is the most effective way to get your point across. Use it.

The Joy of X by Steven Strogatz

• Just as numbers are a shortcut for counting by ones, addition is a shortcut for counting by any amount.
• This is how mathematics grows. The right abstraction leads to new insight, and new power.
• Roman numerals are only slightly more sophisticated than tallies. You can spot the vestige of tallies in the way Romans wrote 2 and 3, as II and III.
• All place-value systems are based on some number called, appropriately enough, the base. Our system is base 10, or decimale. After the ones place, the subsequent consecutive places represent tens, hundreds, thousands, and so on, each of which is a power of 10.
• Our world has been changed by the power of 2. In the past few decades we’ve come to realize that all information--not just numbers, but also language, images, and sound--can be encoded in streams of zeros and ones.
• Algebra is the language in which such patterns are most naturally phrased.
• Complex numbers are magnificent, the pinnacle of number systems. They enjoy all the same properties as real numbers--you can add and subtract them, multiply and divide them--but they are better than real numbers because they always have roots. You can take the square root or cube root or any root of a complex number, and the result will still be a complex number.
• Complex numbers are the culmination of the journey that began with 1.
• Perhaps even more important, word problems give us practice thinking not just about numbers, but about relationships between numbers.
• Relationships are much more abstract than numbers. But they’re also much more powerful. They express the inner logic of the world around us.
• A mathematician needs functions for the same reason that a builder needs hammers and drills. Tools transform things. So do functions.
• Exponential growth is almost unimaginably rapid.
• Parabolic curves and surfaces have an impressive focusing power of their own: each can take parallel incoming waves and focus them at a single point. This feature of their geometry has been very useful in settings where light waves, sound waves, or other signals need to be amplified.
• Sine waves are the atoms of structure. They’re nature’s building blocks. Without them there’d be nothing, giving new meaning to the phrase “sine qua non”.
• The key to thinking mathematically about curved shapes is to pretend they’re made up of lots of little straight pieces. That’s not really true, but it works...as long as you take it to the limit and imagine infinitely many pieces, each infinitesimally small. That’s the crucial idea behind all of calculus.
• Calculus is the mathematics of change. It describes everything from the spread of epidemics to the zigs and zags of a well-throw curveball.
• Roughly speaking, the derivative tells you how fast something is changing; the integral tells you how much it’s accumulating.
• Mathematical signs and symbols are often cryptic, but the bet of them offer visual clues to their own meaning. The symbols for zero, one, and infinity aptly resemble an empty hole, a single mark, and an endless loop.
• How does individual randomness turn into collective regularity? Easy--the odds demand it.
• An idealized version of these bell curves is what mathematicians call the normal distribution. It’s one of the most important concepts in statistics. Part of its appeal is theoretical. The normal distribution can be proven to arise whenever a large number of mildly random effects of similar size, all acting independently, are added together. And many things are like that.
• The normal distribution is not nearly as ubiquitous as it once seemed.
• Power Law distributions have counterintuitive properties from the standpoint of conventional statistics.
• Whether you want to detect patterns in large data sets or perform gigantic computations involving millions of variables, linear algebra has the tools you need.
• One of the central tasks of linear algebra, therefore, is the development of faster and faster algorithms for solving such huge sets of equations. Even slight improvements have ramifications for everything from airline scheduling to image compression.

Why Buildings Fall Down by Matthys Levy and Mario Salvadori

• The accidental death of a building is always due to the failure of its skeleton, the structure.
• A dome may be naively thought to be a series of vertical arches (its meridians) rotated around a vertical axis and sharing a common keystone, and in fact, a dome does carry to earth its own weight and the additional weights on it by such a mechanism. But these imaginary arches are not independent of each other; they are, so to say, glued together and, hence, work together.
• In practice, all structural failures may be considered due to a lack of redundancy.
• THe simplest example of the difference between a stable and an unstable mechanical situation is demonstrated by a marble resting at the bottom of a bowl as against one balanced at the top of the same bowl turned upside down.
• Redundancy implies that a structure can carry loads by more than one mechanism--that is, that the forces on it can follow alternate paths to the ground. It guarantees that if one mechanism fails, loads can still be carried by other mechanisms.
• The earth’s crust is like a broken eggshell floating on the viscous inner magma of melted rock. Plate tectonics, the recently develop theory of movements of the earth’s crust, offers the most plausible explanation for the existence of bands all over the globe along which most earthquakes occur.
• Bricks and concrete blocks joined with a cement mortar are very strong in compression but posses little tensile strength.
• Metal fatigue [is] the weakening of metals subjected to frequent reversal of stresses from tension to compression (from pulling to pushing) and vice versa.
• Aircraft structures are particularly subject to fatigue, caused by the alternative pressurization and depressurization of the hull and the bending of the wings up and down as the plane flies through varying meteorological conditions.
• The danger of fagieu is increased even by the unavoidable microscopic imperfections of the metal, such as minute pinholes or cracks, because stress concentration occurs at all these discontinuities.
• Soils often act as the very worst structural materials, yet we must entrust the support of all our buildings to their strength.
• Only five basic factors influence every structural design and, hence, the safety of all built structures, and each may be totally or partly responsible for a failure. They are:
• Structural theories
• Calculation techniques
• Material properties
• Communication procedures
• Economic factors
• The ancient world achieved amazing feats of structural virtuosity on the basis of a limited knowledge of structural theory.
• A frame structure is one in which beams and columns are rigidly connected, either welded or bolted together.
• With the exception of wood, natural materials suffer from being strong in only tension, like vegetable fibers, or only in compression, like stone.
• The invention of reinforced concrete by French engineers in the middle 1800s produced the first all-purpose artificial material, used today all over the world to build some of our tallest buildings, our largest roofs, and our most economical housing.
• As noted, steel’s increase in strength is all too often accompanied by an increase in brittleness. This brittleness will limit steel’s strength much above that already reached.
• Economic factors have always been of the greatest importance in structural design.
• Ambition, one of the prime movers of human activity, may push us to erect new towers of Babel or to devise better design and construction methods. We must conclude that in the field of structure, as in any other field of human endeavor, technological improvements alone cannot guarantee a decrease of failures and may even increase it. Only a deeper consciousness of our human and social responsibilities can lead to the construction of safer buildings.
• When all is said and done, most of the time structural failures flow from human error, always in concert with physical forces or loads acting on structures. If the earth did not attract, the wind did not blow, the earth’s crust did not shake or settle unevenly, and temperature did not change, there would be no need for today’s structure.
• Architectural structures consist of massive elements, like columns, beams, arches, and domes, and their own load, the so-called dead load, is most of the time the heaviest they must support.
• The evaluation of the dead load of a structure presents the engineer with a paradox: It cannot be computed until the structure is designed, but the structure cannot be designed until the dead load is computed and added to all the other loads.
• The gravity loads the structure must support in addition to its own dead load are called live loads and include the weight of the furniture, people, goods, fixtures, snow, etc.
• Slowly growing loads are called static loads or said to act statically. Other loads, like those caused by winds and earthquakes, grow rapidly or even suddenly; they are called dynamic loads or said to act dynamically. There are the cause of many disastrous structural failures and high losses of life.
• Weight applied dynamically can be equivalent to twice its static weight.
• Loads applied suddenly (like the blow of a hammer on a nail) are called impact loads and can be equivalent to many times their static values; they can be very dangerous unless their dynamic effects are taken into account.
• The effect of a force changing in value depends not only on how fast it changes but on the structure it is applied to. This is so because each structure has a characteristic time of vibration, called its fundamental period or simply its period, and each force will have its own static or dynamic effects on the structure depending on one thing: Does the force reach its maximum value in a time longer or shorter than the structure’s period?
• A tall building oscillates in the wind like an upside down pendulum.
• Varying forces may have a different type of dynamic effect if they are repeatedly applied in rhythm with the period of sthe structure. Such forces are said to be in resonance with the structure and called resonant forces. These rhythmic forces are particularly dangerous, because with repeated rhythmic application the effects accumulate and can reach large values.
• The oscillations of a tall building must sometimes be damped to avoid the inconvenience of airsickness to the occupants. This has recently been done by the use of a gadget first introduced to damped machinery oscillations, called a tuned dynamic damper. The damper action is based on the Newtonian concept of inertia: that a mass tends to stay put (or move at a constant velocity) unless acted upon by a force.
• Violent motions of the earth’s crust, the quaking of the earth, shake buildings and generate high dynamic loads in their structures.
• Loads caused by changes in temperature, thermal loads, and those resulting from uneven settlements of the ground, settlement loads, are particularly insidious because they are not visible, like those caused by gravity, and may be most damaging if neglected.
• We learn in school that when temperature increases, bodies expand and that they contract when temperature decreases.
• The forces acting on a structure can only pull or push on its elements. To speak of these forces in engineering parlance, structural elements can only be put in tension or in compression by tensile (pulling) or compressive (pushing) forces.
• All structural materials are strong i either tension or compression, and one--steel--is equally strong in both.
• Concrete is [...] weak in tension, and this is why French engineers suggested in the 1850s that steel bars be embedded in areas of concrete beams and other structural elements eher loads could develop tension. They thus invented reinforced concrete, which today is the most economical and widely used structural material in the world over.
• A material’s strength in tension or compression is determined by testing how much load each unit area can resist before breaking.
• Engineers are very conservative, as they should be to avoid failure. They will not allow a structural material to “work” at more than a fraction of its ultimate strength. When dealing with static loads, they adopt safety factors on the order of 2--that is, they use working stresses about one-half of the ultimate strength. When considering dynamic loads, they may required coefficients of safety as high as 4 or even larger.
• The greater the uncertainty about the material’s strength, the values of the loads, or the behavior of the structural system, the higher the coefficient of safety.
• In addition to the property of strength, a structural material under load must exhibit two behaviors called elasticity and plasticity. The first requires that when a load is removed from a structural element, the element returns to its original unloaded shape. The need for this requirement is fairy obvious: if, upon unloading, the element remained deformed, the next time it is loaded an additional deformation would appear, and after a number of loadings and unloadings the element would be so deformed as to be unusable. Most structural materials not only behave elastically as demanded by the requirement we have just discussed but also deflect under load in proportion to the load and are said to be linearly elastic. [...] This property is essential since if the deflection is larger than the proportional deflection you expect from linearly elastic behavior, you know that the material is overstressed.
• When a material behaves elastically, the stress is also proportional to the deformation (elongation or shortening) of a unit length of material, which we call the strain.
• Materials that exhibit a permanent deformation after a certain load is reached (called the yield point) and are said to have a plastic behavior above the yield point are preferred because a permanent deformation is the loudest alarm a material can give that it is ready to fail and should not be subjected to additional loads.
• We build structural systems by putting together structural elements made out of structural materials.
• The first requirement of any architectural structure is to stay put, not to move, or as engineers say, to be stable.
• A structure not only must be stable--that is, not be subjected to large displacements--but, except for the tiny changes in the shapes of its parts caused by the forces acting on it, must not move at all; it must be in equilibrium. This requirement implies, of course, that each element of a whole structure must also be in equilibrium so that the structure will stay together.
• A straight element in pure tension is called a tension bar or simply a bar and is used in many industrial buildings and roof designs.
• A cable is a stable structure when used as a vertical hanger pulled by a single load but is unstable when hanging from two points and carrying moving or variable loads because as the loads change position or value, the cable must change shape in order to be able to carry them only by means of tension.
• Cable instability limits the use of cables in architectural structures despite the enormous strength of modern steel cables.
• Cables are the most essential element of large structures like suspension bridges, suspended roofs, balloons, and tents.
• A straight element under pure compression is called a strut and is used mostly in bridges and roofs. When used vertically, a struct is called a column. The column has the basic function of transferring loads to earth.
• The more you pull a bar, the straight it becomes, but if you compress a strut too hard, something unexpected takes place. A thin strut submitted to an axial compressive load will not remain straight but bent out suddenly, or buckle, at a specific value of the compressive load, called its critical or Euler value.
• Today buckling is considered a very dangerous structural phenomena because our strong materials allow us to design thin elements in compression (columns, struts, arches, and domes) that buckle without giving notice.
• If an axe is pushed into a piece of wood, it splits it by pushing out the wood fibers. By the same kind of a wedge-shaped stone pushes out on two adjacent wedge pieces of stone with the force of its own weight and the loads on it. This is why an arch can built with materials strong in compression by means of wedge-shaped stones; it works in compression and stands up, provided its ends are prevented from moving outward by stones anchored in the soil, called abutments.
• Since the inward push, or thrust, of the abutments on the arch is essential to arch action, weak abutments are the most common cause of arch bridge failures.
• A beam is a straight, usually horizontal element capable of transferring vertical loads to its supports horizontally. [...] If such a beam is set on two end supports and loaded at midspan, it deflects in a curved shape, and the distance between the vertical line segments shrinks at the top and lengthens at the bottom. SInce lengthening is always due to tension, and shortening to compression a beam on two supports, or simply supported, develops tension below its neutral axis and compression above it; it is said to work in bending.
• Beams of reinforced concrete must have steel reinforcing bars located where nerve tension may develop under load.
• In steel construction, two basically different types of joints are used, depending on whether one wishes to allow or prevent the relative rotation of adjoining elements are called hinges, while those preventing it are said to be rigid or moment-resisting joints.
• In steel elements, hinges, also called shear joints, are usually obtained by connecting only the web of a steel beam to the supporting columns. Moment connections are obtained by connecting both the web and the flanges.
• The behavior of structures joined by shear connections is totally different from that of structures joined by moment-resisting connections. Moment-resisting joints give the structure monolithicity and greater resistance to lateral forces, like wind and earthquakes, but increase the value of stress caused by changes in temperature and soil settlements. Shear joints weaken structural resistance to lateral loads while reducing the values of thermal and settlement stress.
• Trusses are obtained by joining tension bars and compression struts by means of hinged joints. The variety of such structures is obviously great, but all consist of combinations of the same type of rigid element, a hinged triangle, the simplest rigid shape a structure can have.
• Because moment-resisting connections are more costly than shear connections, many modern high-rise buildings have hinged frames carrying the gravity loads and a central core of reinforced concrete walls, resisting the lateral forces of wind and earthquakes. The hinged frames lean on the core for support against lateral forces and would collapse like a house of card were it not for the bending resistance of the core, which acts like a stiff, tall, thin tower.
• Ballon roofs consist of large plastic membranes, stiffened by steel cables, that are curved in the shape of tensile arches by low air pressure that keeps the membrane up.
• All loads on buildings, including the preponderant dead load, must be supported on earth. If the earth’s surface, as most of us subconsciously expect it to be, were evenly strong and stable, and all soils equally consistent and resistant to compression, the design and construction of foundations would be an easy task. Unfortunately soils have different and variable consistencies so that even in the absence of earthquakes they move.

Why Buildings Stand Up by Mario Salvadori

• Science and technology at their best are motivated to satisfy genuine human needs.
• The purpose of a building is to perform a function. The function of most buildings is to protect people from the weather by creating enclosed but interconnected spaces.
• The development of structural material has not kept pace with the needs for the realization of advanced theoretical concepts Except for reinforced and prestressed concrete and high-strength steel, the materials we use today are very similar to those used by our forefathers.
• Cultures are immortalized by monuments, which express their conception of the world, of life and death.
• The collapse of the Meidum pyramid demonstrates that the problem of loads, of weight distribution, even in apparently simple geometric structures, is a complex, ever-present concert for builders. If the earth did not pull, the wind did not blow, the earth’s surface did not shake or sink, and the air temperature did not change, loads would not exist and structure would be unnecessary.
• Structure supports all the loads that act, unavoidably, on buildings.
• The engineer’s first job is to determine which loads will act on a structure and how strong they might be in extreme cases.
• A structure consists of heavy elements like columns, beams, floors, arches, or domes which must, first of all, support their own weight, the so-called dead load.
• The dead load is a load “permanently there”. In some structures built of masonry or concrete it is often the heaviest load to be supported by the structure.
• In addition to its dead load, a structure must support a variety of other weights--people, furniture, equipment, stored goods. These impermanent or live loads may be shifted around and they may change in value.
• Concern for safety suggests that live loads must be established on the basis of the worst loading conditions one may expect during the entire life of the structure.
• The dead load is permanent and unchanging and the live loads have been tacitly assumed to change slowly, if at all. Together, these unchanging or slowly changing loads are called by engineers static loads, loads that stay.
• But other loads change value rapidly and even abruptly, like the pressure of a wind gust, or the action of an object dropped on the floor. Such loads are called dynamic and may be exceedingly dangerous because they often have a much greater effect than the same loads applied slowly.
• Under the wind pressure the building bends slightly and its top moves. Its movement may be small enough not to be seen by the naked eye, or even sensed, but since structural materials are never totally rigid, all buildings do sway in the wind.
• The time it takes a pendulum to complete a full swing, from extreme right to extreme left and back, is called the period of the pendulum. Similarly, the time it takes a building to swing through a complete oscillations is called its period.
• The action of the gust depends not only on how long it takes to reach its maximum value and decrease again, but on the period of the building on which it acts. If the wind load grows to its maximum value and vanishes in a time much shorter than the period of the building, its effects are dynamic. They are static if the load grows and vanishes in a time much longer than the period of the building.
• Interestingly enough, there are loads which, though not growing rapidly, do have dynamic effects increasing, not instantaneously, but progressively in time. This phenomenon, called resonance, is one of the most dangerous a structure may be subjected to.
• Resonant forces do not produce large effects immediately, as impact forces do, but their effects increase steadily with time and may become catastrophic if they last long enough.
• THe forces exerted by winds on buildings have dramatically increased in importance with the increase in building heights. Stati wind effets rise as the square of a structure’s height.
• One of the basic questions to be resolved before designing a building is often: “What is the strongest wind to be expected at its site?”
• It is wiser to design buildings so that they will be undamaged by a wind with a chance of occuring once in, say, 50 years, but to allow minor damage under the forces of a 100 year wind.
• Besides depending on wind speed and building height, wind forces vary with the shape of the building. The wind exerts a pressure on the windward face of a rectangular building because the movement of the air particles is stopped by this face. The air particles, forced from their original direction, go around the building in order to continue their flow, and get together again behind the building. In so doing, the air particles suck on the leeward face of the building and a negative pressure or suction is exerted on it. The total wind force is the sum of the windward pressure and the leeward suction, but each of these two forces has its own local effects.
• In designing for wind, a building cannot be considered independent of its surroundings. The influence of nearby buildings and of the land configuration can be substantial.
• The swaying of the top of a building due to wind may not be seen by the passerby, but it may feel substantial to those who occupy the top stories of a high building.
• To avoid excessive wind deflections (or wind drift as it is technically called) buildings should be stiffened so that their tops will never swing more than 1/500 of their height.
• The earth’s crust floats over a core of molten rock and some of its parts have a tendency to move with respect to one another. This movement creates stresses in the crust, which may break out along fractures and faults. THe break occurs through a sudden sliding motion in the direction of the fault and jerks the buildings in the area. Since the dynamic impact forces due to this jerky motion are mostly horizontal, they can be resisted by the same kind of bracing used against the wind.
• The last category of loads the engineer must worry about consists of those caused by daily or seasonal change in air temperature or by uneven settlement of the soil under a building. These are sometimes called hidden or locked-in loads.
• On a summer day, when the air temperature reaches 90-degrees, the bridge lengthens, since all bodies expand when heated.
• Unfortunately, steel is so stiff that the compressive load exerted by the abutments uses up half the strength of the steel. There is only one way of avoiding this dangerous overstress: one of the bridge ends must be allowed to move to permit the thermal expansion to occur. While gravity loads must be fought by increasing the strength and stiffness of a structure, thermal loads must be avoided by making the structure less rigid.
• It must be emphasized that most damage to buildings is caused by foundation problems.
• The purpose of structure is to channel the loads on the building to the ground. This action is similar to that of water flowing down a network of pipes; columns, beams, cables, arches, and other structural elements act as pipes for the flow of the loads. Obviously, this becomes a complex function when the structure is large and the loads numerous.
• THe remarkable, inherent simplicity of nature allows the structure to perform its task through two elementary actions only: pulling and pushing. Many and varied as the loads may be and geometrically complicated as the structure may be, its elements never develop any other kind of action. They are either pulled by the loads, and then they are stretched, or are pushed, and then they shorten.
• In structural language, the loads are sid to stress the structure, which strains under stress.
• With a judicious sense of economy, or intelligent laziness, a structure will always choose to channel its loads to the ground by the easiest of the may paths available. This is the path requiring the minimum amount of work on the part of the structural materials and is a consequence of what is termed in physics “the law of least work”.
• When a material is pulled, it is said to be in tension. Tension is easy to recognize because it lengthens the material. [...] We can detect tension easily in elements made of very elastic materials, like a rubber band. Pull on a rubber band and it easily becomes twice its original length.
• When a material is pushed it is said to be in compression. Compression, in a sense, is the opposite of tension, since it shortens the material. If we push on a rectangular sponge, the sponge becomes shorter.
• Structural materials are much stiffer than rubber bands or sponges. Their lengthening under tension or shortening under compression may not be seen by the naked eye, but it always occurs, since there are no perfectly rigid structural materials.
• The tiny changes in length due to tension and compression when divided by the original length of the element are called strains.
• The pull or push on an element, divided by the area it is applied to, is called stress.
• Since all structural actions consist of tension and/or compression, all structural materials must be strong in one or both.
• Strength is not the only property required of all structural materials. Whether the loads act on a structure permanently, intermittently, or only briefly, the lengthening and shortening of its elements must not increase indefinitely and must disappear when the action of the load ends. The first condition guarantees that the material will not stretch or shorten so much that it will eventually break under the working loads. The second insures that the material and , hence, the structure will return to its original shape when unloaded.
• A material whose change in shape vanishes rapidly when the loads on it disappear is said to behave elastically. A rubber band is correctly called an elastic, since it returns to its length when we stop pulling on it. All structural materials must be elastic to a certain extent, although none is perfectly elastic under high loads.
• Most structural materials not only behave elastically, but within limits show deformations that increase in proportion to the loads.
• All structural materials behave elastically if the roads are kept within given limited values. When the loads grow above these values, materials develop deformations larger and no longer proportional to the loads. These deformation, which do not disappear upon unloading, are called permanent or residual deformations. When this happens, the material is said to behave plastically. If the loads kept increasing after the appearance of plastic behavior, materials soon fail.
• If we progressively load a structure and measure its increasing deformations, we are warned that the structure is in danger of collapse as soon as we notice that these deformations grow faster than the loads. IN other words, materials that behave elastically under relatively small loads and plastically under higher loads do not reach their breaking points suddenly. Once they stop behaving elastically, they keep stretching (or shortening) under increasing loads until they continue to do so even without an increase in the loads. Only then they fail.
• Materials which do not yield are called brittle and cannot be used in structures, because they behave elastically up to their breaking point and fail suddenly without any warning.
• Thus, strength, elasticity, and plasticity are all necessary to good structural behavior.
• Steel, the strongest structural material available to man, becomes plastic at high temperatures and loses its strength at 1,200 degrees. Steel buildings must be fireproofed to retard the heating of its columns and beams in a fire. Concrete, instead, is a particularly good insulating material and prevents for a long time the heating and yielding of its reinforcing steel bars. Reinforced concrete buildings do not have to be fireproofed.
• On the other hand, at a temperature of minus 30 degrees, called its transition temperature, steel becomes brittle and breaks suddenly, particularly under impact, or suddenly increased, loads.
• The strength of  a structural material is measured by the number of pounds each square inch of material will carry before it breaks. This number, similar to hose measuring stress, is called its ultimate strength and varies from material to material and even in the same material depending on how it is stressed.
• Pound per pound, steel is the material with the greatest strength obtainable at the lowest price.
• Steel is an alloy of iron and carbon, with very tiny amounts of other metals to give it particular properties.
• In welding, the steel of the two parts to be connected is melted at high temperature and a welding metal is deposited at the joint. WHen a well-executed joint cools, the connection becomes as strong as the steel of the jointed pieces. The high temperatures used in welding, if reached or cooled too rapidly and concentrated in too small an area around the joint, may produce thermal locked-in stresses, which the steel is unable to resist.
• It must be remembered that steel is “fatigued” by reversal of stress from tension to compression and vice versa, when this cycle is repeated many times. We use this phenomenon ourselves to break wire by bending it back and forth a number of times.
• Possibly the most interesting man-made structural material is reinforced concrete. Combing the compressive strength of concrete and the tensile strength of steel, it can be poured into forms and given any shape suitable to the channeling of loads. It can be sculpted to the wishes of the architect rather than assembled in prefabricated shapes. It is economical, available almost everywhere, fire-resistant, and can be designed to be lightweight to reduce the dead load or to have a whole gamut of strengths to satisfy structural needs.
• Concrete is a mixture of cement, sand, crushed stone or pebbles, and water. The water and cement past fills the voids between the grains of sand and these fill the voids between the stones. After a few days the cement paste starts to harden or set and at the end of four weeks it gives concrete its nominal ultimate strength, which is as good as that of some of the strongest stones.
• Portland cement, as modern cement is called, is a mixture of limestone and clay, burned in a furnace and then pulverized. IMpervious to water, it actually becomes stronger if submerged after it hardens.
• IN reinforced concrete, bars of steel are embedded in the concrete in those areas where pulls will develop under loads, so that the steel takes the tension and concrete the compression.
• Plastics can be made as strong as steel in both tension and compression, can be given an elastic or a plastic behavior, and are practically indestructible. AMong the most useful plastics are those reinforced by glass fibers, like Fiberglass, which are shatterproof because glass, extremely strong in tension, has its brittleness cushioned by the plastic matrix in which it is embedded.
• Since we want our structures not to move, except for the miniscule displacements due to their elasticity, Newton’s laws of rest are the fundamental laws ruling the balance that must exist between all the forces applied to a structure.
• IN physics a body at rest is said to be in equilibrium, from the identical Latin word which means “equal weights” or balance. An understanding of two particularly simple aspects of the laws of equilibrium is essential to an insight into how structures work.
• Simple as this may seem, the task of the structure is to guarantee translational and rotational equilibrium of the building under the action of any and all forces and reactions applied to it, including, of course, its own weight. The task of the engineer is to shape and dimension the chosen structural materials so that the structure may produce equilibrium without breaking up, and with acceptably small elastic displacements.
• I-beams of steel with wide flanges, called wide-flange sections, are obtained by rolling heated and softened pieces of steel between the jaws of powerful presses and have flanges much wider than the top and bottom segments of a capital ‘I’. This is the most efficient shape a beam can be given to carry vertical loads horizontally from one point to another. One may think of a beam as a structural element that transfers vertical loads to the end supports along is horizontal fibers, as if the beam deflected the vertical flow of the loads by ninety degrees only to turn them around again in a vertical direction at the beam supports.
• Deep beams are stiffer than shallow beams. ON the other hand, the beam stiffness diminished dramatically with increases in length; doubling the length of a beam makes it sixteen times more flexible.
• When a beam’s ends curve up, as in a beam supported at its ends, its lower fibers are in tension and its upper fibers in compression. Whenever a beam curves down, like a cantilever, the upper fibers are in tension and the lower in compression.
• The moment a column bends out, the compressive force acquires a lever arm with respect to its axis and bends it progressively more. THis is a chain reaction where the more the column bends, the larger the lever arm becomes. This increases the bending action of the force, which increases the lever arm, and so on. Very soon the column fails in bending. The column is said to become unstable when the load reached its critical value.
• Since buckling is a phenomenon involving bending, it becomes clear why modern steel columns have the shape of wide-flange beams. Their resistance to buckling is magnified by this shape without a costly increase in material.
• Buckling is one of the main causes of structural failure.
• One of the most dangerous characteristics of a buckling failure is its suddenness, which gives no warning. Whenever a structure under load chooses the easy path of benign rather than the foressen path of compression, the structure may fail.
• Very thin, flexible elements can work only in tension. Strings and cables are so flexible that they cannot resist compression or bending, as a beam does. They can only resist pulls, and since they straighten when pulled, they are always straight between hanging loads. This is why, in order to carry loads by tension only, cables must change shape whenever loads change in location or number.
• Suspension bridges are the kings of the bridge world. No other method of construction can span greater distances. Their use of materials is totally logical.
• No large roof can be built by means of natural or man-made compressive materials without giving the roof a curved shape, and this is why domes were used before any other type of cover to achieve large enclosed spaces.
• Genius often consists of an ability to take the next step.
• Whether supported over the crossing of a church or directly on the ground, the dome must carry its own weight and the weight of the live load, including the pressure and suction of the wind and, in northern climates, the weight of snow.
• What makes the dome behave differently is the fact the the hypothetical arches it consists of are joined together along the vertical sections of the dome, making it a monolithic structure.
• Most domes are stiffened at their bottom by a strong ring, which to all practical purposes restrains the motion there.
• The compression strength of concrete--the most commonly used structural material the world over--has increased dramatically in the last few decades.
• Most limitations in construction are due to economic rather than technological factors.

Language Implementation Patterns by Terence Parr

• The truth is that the architecture of most language applications is freakishly similar.
• A good way to learn about language design is to look at lots of different languages.
• A domain-specific language is just that: a computer language designed to make users particularly productive in a specific domain.
• Many algorithms and processes are inherently recursive.
• A language is just a set of valid sentences.
• A reader builds a data structure from one or more input streams. The input streams are usually text but can be binary data as well.
• A generator walks an internal data structure and emits output.
• A translator reads text or binary input and emits output conforming to the same or a different language. It is essentially a combined reader and generator.
• An interpreter reads, decodes, and executes instructions.
• Some languages are tougher to parse than others, and so we need parsers of varying strength. The trade-off is that the stronger parsing patterns are more complicated and sometimes  a bit slower.
• Backtracking strength comes at the cost of slow execution speed.
• Rather than repeatedly parsing the input text in every stage, we’ll construct an IR. The IR is a highly processed version of the input text that’s easy to traverse.
• An abstract-syntax tree (AST) has a node for every important token and uses operators as subtree roots.
• There are four common kinds of scoping rules: languages with a single scope, nested scopes, C-style struct scopes, and class scopes.
• Interpreters execute instructions stored in the AST but usually need other data structures too, like a symbol table.
• The more you know about existing language applications, the easier it’ll be to design your own.
• An interpreter is a program that executes other programs. In effect, an interpreter simulates a hardware processor in software, which is why we call them virtual machines. An interpreter’s instruction set is typically pretty low level but higher level than raw machine code. We call the instructions bytecodes because we can represent each instruction with a unique integer code from 0...255 (a byte’s range).
• To execute a program, the interpreter uses a fetch-decode-execute cycle.
• Self-assignment is when we assign a variable to itself.
• All the scary voodoo within a compiler happens inside the semantic analyzer and optimizer.
• Just as a parser is the key to analyzing the syntax, a symbol table is the key to understanding the semantics (meaning) of the input. In a nutshell, syntax tells us what to do, and semantics tells us what to do it to.
• Having an AST lets us sniff the input multiple times without having to reparse it, which would be pretty inefficient.
• The act of recognizing a phrase by computer is called parsing.
• Parse trees are important because they tell us everything we need to know about the syntax (structure) of a phrase.
• A parser checks whether a sentence conforms to the syntax of a language.
• Building recursive-descent parsers in a general-purpose programming language is tedious and error-prone.
• Tools that translate grammers to parsers are called parser generators.
• Grammars are concise and act like functional specifications for languages.
• Recognizers that feed off character streams are called tokenizers or lexers.
• Just as an overall sentence has structure, the individual tokens have structure. At the character level, we refer to syntax as the lexical structure.
• The more powerful the underlying recognition strategy, the easier it is to write a grammar. That is because more powerful parsing strategies allow a larger set of grammars.
• Lexers derive a stream of tokens from a character stream by recognizing lexical patterns.
• Lexers are also called scanners, lexical analyzers, and tokenizers.
• The goal of the lexer is to emit a sequence of tokens. Each token has two primary attributes: a token type (symbol category) and the text associated with it.
• Having more lookahead is like being able to see farther down multiple paths emanating from a fork in a maze.
• The simplest way to provide lots of parser lookahead is to buffer up all the input tokens.
• A backtracking parser attempts alternatives in order until one of them matches the current input.
• A context-free language is a language whose constructs don’t depend on the presence of other constructs.
• Using exceptions for control flow is usually a very bad idea because they act like gotos.
• The heart of a backtracking parser lies in its token buffer management. The buffer must handle an arbitrary amount of lookahead and support nested mark and release operations. The easiest way to deal with arbitrary lookahead is simple to buffer up the entire token stream.
• Compiler writers often leverage an existing optimizer and code generator by translating multiple languages to an established IR.
• Not all programming language constructs map directly to executable code.
• The best way to create ASTs and to verify their structure is with a formal mechanism.
• A parse tree describes how a parser recognized an input sentence.
• Compiler optimizers try to reduce operations to simpler equivalents in an effort to generate faster code.
• To enforce language semantics, we need to track symbol definitions and be able to identify those symbols later.
• A symbol is just a name for a program entity like a variable or method.
• Language applications track symbols in an abstract data structure called a symbol table.
• Scopes start and end at the start and end of language structures such as functions.
• A scope is a code region with a well-defined boundary that groups symbol definitions (in a dictionary associated with that code region).
• Scope boundaries usually coincide with begin and end tokens such as curly braces. We call this lexical scoping because the extent of a scope is lexically delimited.
• Think of dynamic scoping as allowing methods to see the local variables of invoking methods.
• To avoid ambiguity, programming languages use context to figure out which symbol we’re talking about. Context corresponds to the scope surrounding the symbol and any enclosing scopes.
• To track nested scopes, we push and pop scopes onto a scope stack.
• A forward reference is a reference to a method, type, or variable defined later in the input file.
• The goal of automatic type promotion is to get all operands of a single operation to be of the same type or compatible types.
• A language application can convert between types at will as long as it doesn’t lose information. We call such automatic conversion promotion because we can widen types without problem but can’t narrow them in general.
• Polymorphism means that a pointer can refer to objects of multiple types.
• To execute a program not written in machine code, we’ve got to interpret the program or translate it to the equivalent program in a language that already runs on that machine.
• High-level interpreters directly execute source code instructions or the AST equivalent. Low-level interpreter execute instructions called bytecodes that are close to CPU machine instructions.
• Usually, simplicity and low-cost implementation trump execution efficiency for DSLs.
• Function calls save return addresses so they can return to the instruction following the function call.
• There are three things to consider when building an interpreter: how to store data, how and when to track symbols, and how to execute instructions.
• High-level interpreters store values according to value names, not memory addresses (like low-level interpreters and CPUs do). That means we’ve got to represent memory with a dictionary mapping names to values.
• The basic idea behind executing instructions is called the fetch-decode-execute cycle. First, we load an instruction from code memory. Then, we decode the instruction to find the operation and operands. Finally, we execute the operation. Rinse and repeat. Ultimately the interpreter runs out of interpreter in the main program, or it executes a halt instruction.
• The more highly we process the program before execution, the faster it will go at run-time.
• Bytecode interpreters have a number of useful characteristics including portability.
• Adding specialized instructions for common operations is the easiest way to speed up an interpreter.
• The only real difference between a register and a stack machine is in the way we program them. We either load operands into registers or push them onto the stack; the difference is as simple as that.
• The instruction pointer is a special-purpose “register” that points into code memory at the next instruction to execute.
• To execute instructions, the interpreter has a simulated CPU that amounts to a loop around a giant “switch on bytecode” statement. This is called the instruction dispatcher.
• The interpreter has a stack to hold function call return addresses as well as parameters and local variables.
• The processor is the heart of an interpreter and has a simple job: it loops around a fetch-decode-execute mechanism.
• The CPU stops when it hits a halt instruction or runs out of instructions to execute at the end of the code memory.
• Bytecode interpreters store strings and other non integer constants in a constant pool.
• The constant pool is just an array of objects and is commonly used by bytecode interpreters.
• A stack frame is an object that tracks information about a function call.
• One of the things you’ll discover quickly when reading source code or building your own interpreter is that making an interpreter go really fast is not easy. Every CPU clock cycle and memory access counts.
• Register machines can often execute high-level programs faster than stack machines.
• Bytecode interpreters feed off low-level byte arrays full of bytecodes (operation codes that fit into a byte) and integer operands.
• Bytecode interpreters don’t know anything about symbols. For speed reasons, they only deal with code addresses, data addresses, and constant pool indexes.
• To jump around an assembly language program, branch instructions use code label operands. A code label is just a symbol that makes a location in code memory and saves the programmer from having to manually compute addresses.
• A stack-based bytecode interpreter simulates a hardware processor with no general-purpose registers. That means that bytecode instructions must use an operand stack to hold temporary values.
• To return a value, a function pushes a value onto the operand stack and then execute the ‘ret’ instruction.
• The biggest speed impediment for a stack-based interpreter is the extra work involved in constantly flicking the operand stack.
• Building an interpreter is one way to implement a language, but we can also build a translator from the new language to an existing language.
• One of the most important lessons I’ve learned over the years is that we should compute information and translate phrases when it’s convenient and efficient to do so, not when the output order demands it.
• There are two key components to implementing this DSL: the translator itself and the run-time support.
• The basic idea in an object-to-relational database mapping is to translate classes to tables and fields to columns in the corresponding table.

CODE by Charles Petzold

• The word code usually means a system for transferring information among people and machines. In other words, a code lets you communicate. Sometimes we think of codes as secret. But most codes are not. Indeed, most codes must be well understood because they're the basis of human communication.
• Two different anything, really, can with suitable combinations convey all types of information.
• Just as Morse code provides a good introduction to the nature of codes, the telegraph provides a good introductions to the hardware of the computer.
• The prevailing scientific wisdom regarding the working of electricity is called the electron theory, which says that electricity derives from the movement of electrons.
• The invention of the telegraph truly marks the beginning of modern communication. For the first time, people were able to communicate further than the eye could see or the ear could hear and faster than a horse could gallop.
• Using a base-ten, or decimal, number system is completely arbitrary. Yet we endow numbers based on ten with an almost magical significance and give them special names.
• The lowly zero is without a doubt one of the most important inventions in the history of numbers and mathematics. It supports positional notation because it allows differentiation of 25 from 205 and 250. The zero also eases many mathematical operations that are awkward in non-positional systems, particularly multiplication and division.
• By reducing our number system to just the binary digits 0 and 1, we've gone as far as we can go. We can't get any simpler. Moreover, the binary number system bridges the gap between arithmetic and electricity.
• A wire can be a binary digit. If current is flowing through the wire, the binary digit is 1. If not, the binary digit is 0.
• What's special about binary is that it's the simplest number system possible. There are only two binary digits--0 and 1. If we want something simpler than binary, we'll have to get rid of the 1, and then we'll be left with just a 0. We can't do much of anything with just a 0.
• The word noise is used in communication theory to refer to anything that interferes with communication.
• The essential concept here is that information represents a choice among two or more possibilities.
• The flip side of this is that any information that can be reduced to a choice among two or more possibilities can be expressed using bits.
• Binary numbers can be either signed or unsigned. Unsigned 8-bit numbers range from 0 through 255. Signed 8-bit numbers range from -128 through 127. Nothing about the numbers themselves will tell you whether they're signed or unsigned.
• A flip-flop circuit retains information. It "remembers".
• A processor includes a register called the Program Counter that contains the memory address the processor uses to retrieve the instructions that it executes. Normally the program counter causes the processor to execute instructions that are located sequentially in memory. But some instructions--usually named jump or branch or GOTO--cause the processor to deviate from this steady course. Such instructions cause the program counter to be loaded with another value. The next instruction that the processor fetches is somewhere else in memory.
• The call and return instructions are extremely important features of any processor. They allow a programmer to implement subroutines, which are snipets of frequently used code. Subroutines are the primary organizational elements of assembly-language programs.
• Bandwidth is an extremely important concept in communication, and it relates to the amount of information that can be transferred over a particular communication medium.
• In object-oriented programming, an object is a combination of code and data. The actual way in which the data in an object is stored is understood only by code associated with the object. Objects communicate with one another by sending and receiving messages, which give instructions to an object or ask for information from it.