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Collisions are violations of the pairwise non-intersection constraint between bodies. Collision forces are Lagrange multipliers of these constraints. Collision normals are the (normalized) partial derivatives of the constraint

function wrt one of the body's configurations.

origin/master

e8f8ace824107d51a5cd10c799ec07261027b4be

in 1784 when edmund cartwright saw the mechanical turk play chess he was like "fuck it, if machines can play chess, they can weave" and then invented the mechanical loom

“A threshold concept can be considered as akin to a portal, opening up a new and previously inaccessible way of thinking about something. It represents a transformed way of understanding, or interpreting, or viewing something without which the learner cannot progress.”

In the isolated hamlets in the southern forests, infants were kept in continuous bodily contact with mothers or the mothers' friends--on laps when they were seated, on hips, under arms, against backs, or on shoulders when they were standing. Even during intensive food preparation, or when heavy loads were being moved, babies were not put down. They had priority. There was always a place for them against the body of a 'mother' or close associate. Loads could be shed or lightened, but babies were simply not put down, not deprived of constant, ever-ready, interactive body contact--even when the group was on the move under difficult conditions. Babies responded to this blanket of ever-ready empathetic tactile stimulation by tactile responses of their own. Very quickly they began assembling a sophisticated tactile-speech to transmit desires, needs, and states of mind. They didn't whine or cry to get attention; they touched. While babies everywhere are liminally aware, the constant empathetic tactile contact required to produce a sophisticated type of preverbal communication is rare--except among preconquest peoples. Eliciting delight from babies was a desired social norm, and attentive tactile stimulation was the daily lot of infants. It included protracted body-to-body caressing, snuggling, oral sensuality, hugging, fondling, and kissing. The seductive aspect of the play was frequently collective as older children singly or in combination used their inventive wiles to delight a baby. In their hamlets crying might be heard in reaction to accidental pain, but I don't recall a single case of disgruntled whining or demanding crying.

A few days later the following happened. Solzhenitsyn was arrested. Suren Arakelov, a loyal disciple and follower of his great teacher [Shafarevich], decided to fight the regime. He made two posters - on his chest and on his back - with the inscription: “Freedom for Alexander Solzhenitsyn” and went to Red Square. There he was arrested and sent straight to the Serbsky Psychiatry Institute. He was discharged a couple of years later. Igor Rostislavovich [Shafarevich] came to visit him and was amazed at the change that had occurred. The inner fire of his soul was trampled and extinguished. He was not interested in mathematics, or politics, or even the attention of his once beloved teacher. After a while he got married, found some routine job and turned into an average man. On this occasion the specialists from the Serbsky Institute have brilliantly demonstrated their professional competence. They turned a genius into a “normal” mediocrity.

  • Data.Category: embedded category theory in haskell that only uses arrows, no objects

  • Scrivener

  • J C Butcher: numerical methods for ODEs: Does a mathematical analysis of ODE theory.

  • Pixel art tutorial

  • molikto's weblog on dependently typed languages

  • Endless Loops: Detecting and Animating Periodic Patterns in Still Images

  • Threfthen and Bau: numerical linear algebra, is more like finite dimension functional analysis with algorithms. Good for self-study because many exercises.

  • P=NP upto sharing

  • What is a spinor mathematically

  • Dependently typed schemes.

  • Dependently typed Forth.

  • Study the KISS package manager to learn bash

  • "If a statementis false, it has no evidence" --- nice way to think of Not a = a -> Void.

  • Elimination with a motive in Coq

  • Example of left-inverse that is not a right inverse: parse and print. parse(print(e)) = e can be achieved easily by printing into a legal parseable format. On the other hand, print(parse(s)) = s is much harder, since for example, print(parse("1+2")) = "1 + 2", while "1+2" != "1 + 2".

  • Pollack-inconsistency:To make these issues concrete we introduce the notion of Pollack-consistency. This property is related to a system being able to correctly parse formulas that it printed itself. In current systems it happens regularly that this fails. We argue that a good interactive theorem prover should be Pollack-consistent. We show with examples that many interactive theorem provers currently are not Pollack-consistent. Finally we describe a simple approach for making a system Pollack-consistent, which only consists of a small modification to the printing code of the system.

  • Computational aspects of the mobius transform

  • Why PDE is infinite dimensional: The solution to an ordinary differential equation, of order n, can be written as a linear combination of n independent solutions, with n undetermined constants- a vector space of dimension n. The solution to a partial differential equation, of order n, can be written as a linear combination of n independent solutions but with n undetermined functions. The functions themselves constitute an infinite dimensional vector space. Source https://www.physicsforums.com/threads/why-a-pde-is-an-infinite-dimensional-system.479880/

  • Universes ala Rusell and Tarski

  • Spock's law: A difference that makes no difference is no difference.

  • The thing I find fascinating from a sociology perspective about ransomware is that they have to. To be a successful ransomware company, you have to simultaneously be: 1. Completely immoral enough to attack companies, hold their data ransom and potentially put them out of business and reveal the private details of thousands of people. 2. Create enough trust in the company you attacked that they believe you will give the data back once you pay them. It is crazy that they are psychologically savvy enough to simultaneously attain those directly conflicting goals. In a cynical telling this is how you start a government or any organization with a monopoly on violence, ala mafia. First you make it clear that you can cause damage, then you make it clear that tax payers are safe. The next step for ransomware companies is to offer cyber security services, whether you want them or not. We've hacked you. We fixed your crappy unpatched software, if you try to remove us you lose all your data, so now we're your cyber security partners.

  • Chernoff face Chernoff faces, invented by applied mathematician, statistician and physicist Herman Chernoff in 1973, display multivariate data in the shape of a human face. The individual parts, such as eyes, ears, mouth and nose represent values of the variables by their shape, size, placement and orientation. The idea behind using faces is that humans easily recognize faces and notice small changes without difficulty.

  • Notes on Categorical logic

  • Implementing dependently typed languages

  • Different parts of the lambda cube

  • A key part of these productive ecosystems is jobs. If you want to learn how to build bridges, you do not set up schools to teach engineering, you fund the building of bridges, and people will figure out how to build them on the job, and the demand for civil engineers will pull students to study this and then universities will open up programs to cater to that demand. The jobs come first. Only 5% of China's population attends university, yet they are able to build all the infrastructure they need because they have a laser like attention to creating jobs. They will even build bridges for America, as long as Chinese workers get to make them. They will build a port for anyone who wants it, as long as Chinese workers are the ones building the port. The entire Belt and Road initiative is an attempt to import infrastructure jobs by sending workers all over the world to build infrastructure, as long as China gets to build it. They know that half these projects will default and not make any money, but what they get out of that is a skilled workforce, and with a skilled workforce they can do anything. They will let American companies set up factories in China as long as there is a knowledge transfer as part of the deal. That all their state owned enterprises are losing money is not important, the acquisition of skills and the creation of productive ecosystems is what matters. I wonder when the US will realize this. Western economic thinking is focused on P&L, rule of law, etc, and assumes as an article of faith that in such an environment, productive ecosystems will just arise all on their own, like rats being created from piles of trash. It will just happen, because in the past it just happened. So we are focused on abstract principles, but what the last 30 years has shown us is productive ecosystems being destroyed right and left as production migrates over to Asia.

  • Adding sum types to the bidirectional system breaks this characterization: two terms equivalent up to (some) commuting conversions may both be typable. To fix this, one can try and find type theories in which the commuting conversions no longer preserve equality. By adding (abstract) effects to the language, terms that used to be equivalent can now be distinguished, ensuring that term equality once again coincides with semantic equality. This is the key idea embodied in what is variously called polarized type theory, focalization, or call-by-push-value.

  • Damas–Milner type inference [Damas and Milner 1982] allows only prefix polymorphism. This is a nice way to describe the difference between ∀ a (∀ b, a -> b -> a) versus ∀ a a -> (∀ b. b -> a). . This restriction is called prefix or prenex polymorphism. In their terminology, types contain no quantifiers at all; only type schemes can have quantifiers (on the outside). Polymorphism can be introduced only on let expressions.

  • Pronounce f.g as f after g.

  • US army: ADVANCED SITUATIONAL AWARENESS

  • Nonlinear dispersive equations: local and global analysis

  • Threaded code for faster interpreters --- The Structure and Performance of Efficient Interpreters},

  • Paul Taylor: more exposition of topology of computation. In particular, abstract stone duality

  • Spheres as cogroup objects: A such that hom(a, -) spits out groups -Something other than spheres for homotopy groups

  • Sheaves, cosheaves, and applications

  • Some kids grow up on football. I grew up on public speaking (as behavioral therapy for a speech impediment, actually). If you want to get radically better in a hurry: 1) If you ever find yourself buffering on output, rather than making hesitation noises, just pause. People will read that as considered deliberation and intelligence. It's outrageously more effective than the equivalent amount of emm, aww, like, etc. Practice saying nothing. Nothing is often the best possible thing to say. (A great time to say nothing: during applause or laughter.) 2) People remember voice a heck of a lot more than they remember content. Not vocal voice, but your authorial voice, the sort of thing English teachers teach you to detect in written documents. After you have found a voice which works for you and your typical audiences, you can exploit it to the hilt. I have basically one way to start speeches: with a self-deprecating joke. It almost always gets a laugh out of the crowd, and I can't be nervous when people are laughing with me, so that helps break the ice and warm us into the main topic. 3) Posture hacks: if you're addressing any group of people larger than a dinner table, pick three people in the left, middle, and right of the crowd. Those three people are your new best friends, who have come to hear you talk but for some strange reason are surrounded by great masses of mammals who are uninvolved in the speech. Funny that. Rotate eye contact over your three best friends as you talk, at whatever a natural pace would be for you. (If you don't know what a natural pace is, two sentences or so works for me to a first approximation.) Everyone in the audience -- both your friends and the uninvolved mammals -- will perceive that you are looking directly at them for enough of the speech to feel flattered but not quite enough to feel creepy. 4) Podiums were invented by some sadist who hates introverts. Don't give him the satisfaction. Speak from a vantage point where the crowd can see your entire body. 5) Hands: pockets, no, pens, no, fidgeting, no. Gestures, yes. If you don't have enough gross motor control to talk and gesture at the same time (no joke, this was once a problem for me) then having them in a neutral position in front of your body works well. 6) Many people have different thoughts on the level of preparation or memorization which is required. In general, having strong control of the narrative structure of your speech without being wedded to the exact ordering of sentences is a good balance for most people. (The fact that you're coming to the conclusion shouldn't surprise you.) 7) If you remember nothing else on microtactical phrasing when you're up there, remember that most people do not naturally include enough transition words when speaking informally, which tends to make speeches loose narrative cohesion. Throw in a few more than you would ordinarily think to do. ("Another example of this...", "This is why...", "Furthermore...", etc etc.)

  • Dynamical systems that sort lists, diagonalize matrices, and solve LP problems

  • A compact kernel for the calculus of inductive constructions

  • Hanging pawns: Chess middle games

  • Algebraic K theory: youtube lectures. It seems that K theory automagically forces homotopy of CW complexes when computing the zeroth K-theory.

  • I remember attending two lectures by M. Gromov that began by the remark that not only 4 equals 2 plus 2, but this equality is true in 3 different ways (meaning that there are three equipartitions in two classes of a 4-element set). According to him, a lot of exceptional behaviors in math stem from this, especially from the fact that 3 < 4 (it definitely explains why the alternating group A(4) isn't simple, but Gromov also mentioned the gauge-theoretic oddities in dimension 4). MathOverflow answer

  • Learn how to use linux with HOWTOs.

  • Programming and proving in Agda: https://github.com/jespercockx/agda-lecture-notes/blob/master/agda.pdf

  • Hereditary substitution

  • Categorical logic and type theory by Bart Jacobs.

  • tinyxyz cute animation using tan

  • Packet life: networks cheat sheets

  • Lexicon branding: company that discovers brand names

  • Ideal divisors: fast conversion of division into multiplication, plus p-adic goodness from dan piponi

  • FnV hash: good (non-crypto) fast hash function

  • Macrame knots: pretty knot patterns

  • MicroUI

  • Write your own OS: videos

  • Syntax agreement: learn how to make sentences that meander. In particular, the problem I seem to have is that I am unable to continue half written thoughts in a manner that is coherent overall. Practice this! Normally I feel very nut to crack. I ought to write sentences like the previous version, which are very rising sea.

  • Medeival literature on lying, IP = PSPACE, arithmetization, and Dialogiones

  • Passion of the western mind

  • Gutta percha and the Gutta Percha Company.

  • nanoscale views: cool blog post about berry phase

  • Suffle Automata

  • Find out how opaleye works.

  • Write software rasterizer to render this image

  • STONITH: Shoot The Other Node In The Head.

  • Find instances of countries which used to be corrupt, that no longer is corrupt. Use systems that anonymize who sends the systems. So for example, anonymize the application form so that you don't know who is processing your form, and thus you can't bribe them.

  • Higher dimensional type theory 2020: CubicalTT

  • Hitch-hiker's guide to reinventing a prolog machine

We take a fresh, "clean-room" look at implementing Prolog by deriving its translation to an executable representation and its execution algorithm from a simple Horn Clause meta-interpreter. The resulting design has some interesting properties. The heap representation of terms and the abstract machine instruction encodings are the same. No dedicated code area is used as the code is placed directly on the heap. Unification and indexing operations are orthogonal. Filtering of matching clauses happens without building new structures on the heap. Variables in function and predicate symbol positions are handled with no performance penalty. A simple English-like syntax is used as an intermediate representation for clauses and goals and the same simple syntax can be used by programmers directly as an alternative to classic Prolog syntax. Solutions of (multiple) logic engines are exposed as answer streams that can be combined through typical functional programming patterns, with flexibility to stop, resume, encapsulate and interleave executions. Performance of a basic interpreter implementing our design is within a factor of 2 of a highly optimized compiled WAM-based system using the same host language. To help placing our design on the fairly rich map of Prolog systems, we discuss similarities to existing Prolog abstract machines, with emphasis on separating necessary commonalities from arbitrary implementation choices.

  • Multidimensional Real Analysis I: J. J. Duistermaat. Gives the extrinsic definition of a manifold.
  • Read everything by Ken Perlin
  • Spanier's algebraic topology. It's highly rigorous (just like an analysis or algebra book), and many results are formulated in categorical languages. Besides, assumptions are often as weak as possible. simplicial complexes are used extensively.
  • Dieck's Algebraic Topology is great. It is very rigorous, presents an incredibly wide range of topics, uses (admittedly minimal) categorical language, and gives a much more homotopical perspective on many things.
  • The asses of Parnassus: Short poetry
  • DSP MIT OCW
  • A pangram (sentence will all letters): "Sphinx of black quartz, judge my vow"
  • Ringelmann effect: Why groups may not be effective

The Ringelmann effect is the tendency for individual members of a group to become increasingly less productive as the size of their group increases. This effect, discovered by French agricultural engineer Maximilien Ringelmann (1861–1931), illustrates the inverse relationship that exists between the size of a group and the magnitude of group members’ individual contribution to the completion of a task. While studying the relationship between process loss (i.e., reductions in performance effectiveness or efficiency) and group productivity, Ringelmann (1913) found that having group members work together on a task (e.g., pulling a rope) actually results in significantly less effort than when individual members are acting alone. Ringelmann discovered that as more and more people are added to a group, the group often becomes increasingly inefficient, ultimately violating the notion that group effort and team participation reliably leads to increased effort on behalf of the members.

"Language makes thought possible. When the words disappear, so does our ability to think about the ideas the words represent. When they prevent you from saying the obvious, overtime it becomes impossible to see the obvious.... those who control your words control your mind."

Corb was a very good friend. His numerous letters and postcards and a constant stream of his paintings and drawings, that he sent me until his death, showed me how seriously he treated friendship. He said living was an art.

What became challenging for all these universities once they started emphasizing research is how to incentivize that activity. One thing that agency theory shows is that one way to achieve this is to create somewhat lumpy rewards. That is to say, rewards that don’t necessarily give you a little bit more for a little bit more output but rather create a big prize. Tenure has that flavor. It basically says if your research output is high enough you’re going to get a lifetime contract at this university. Tenure has a couple of benefits that come out of agency theory. One is that these types of lumpy rewards can be particularly good when you make people compete against each other. The emergence of it in the US, in fact, helped place the US on good footing to compete at research with Europe, which does not have that institution as much. US university system, which he calls a “perfect mess.” He says it's a mess, but it's a perfect mess, and it's kind of a contradiction. I think that the good side of the US is that it produces a variety of institutions that can do a variety of tasks relatively well. It produces 50 to 100 that do research extremely well and lead the world in this dimension. It produces other schools, to cite the work of Raj Chetty and coauthors, that generate a lot of mobility. This is not a mess that a social planner would have designed necessarily, but the different parts work well.

!? an interesting move that may or may not be good ?! a dubious move or move that is probably an inaccuracy

  • Remembering White's queenside and kingside:

from White's left (the queenside) to right (the kingside). "queen on her own color", "white on right". Casting kingside is O-O because 2pieces are swapped. Castling queenside is O-O-O because the queen is in the "middle".

"Will no one rid me of this turbulent priest?" (also expressed as "troublesome priest" or "meddlesome priest") is a quote attributed to Henry II of England preceding the death of Thomas Becket, the Archbishop of Canterbury, in 1170. While the quote was not expressed as an order, it prompted four knights to travel from Normandy to Canterbury, where they killed Becket. The phrase is commonly used in modern-day contexts to express that a ruler's wish may be interpreted as a command by his or her subordinates.

Basically, the rates jumped from 2 percent, till they stabilized at the "real rate" of 12 percent.

There are three elements shared by most theorists of agonism: constitutive pluralism, a tragic view of the world, and a belief in the value of conflict.[1] Constitutive pluralism holds that there is no universal measure of adjudicating between conflicting political values.[2] For example, Chantal Mouffe argues, following Carl Schmitt, that politics is built on the distinction of 'us' and 'them'.[3] Based on this, agonists also believe in "a tragic notion of the world without hope of final redemption from suffering and strife", which cannot find a lasting political solution for all conflicts.[4] Instead, agonists see conflict as a political good.[5][6] For example, Mouffe argues that "In a democratic polity, conflicts and confrontations, far from being a sign of imperfection, indicate that democracy is alive and inhabited by pluralism”.[7]

“The end of the walking stick is at the bottom.”

D. Bennequin and P. Baudot introduced a cohomological construction adapted to information theory, called "information cohomology" (see "The homological nature of Entropy", 2015). Our text serves as a detailed introduction to information cohomology, containing the necessary background in probability theory and homological algebra. It makes explicit the link with topos theory, as introduced by Grothendieck, Verdier and their collaborators in the SGA IV. It also contains several new constructions and results. (1) We define generalized information structures, as categories of finite random variables related by a notion of extension or refinement; probability spaces are models (or representations) for these general structures. Generalized information structures form a category with finite products and coproducts. We prove that information cohomology is invariant under isomorphisms of generalized structures. (2) We prove that the relatively-free bar construction gives a projective object for the computation of cohomology. (3) We provide detailed computations of H1 and describe the "degenerate" cases. (4) We establish the homological nature of Tsallis entropy. (5) We re-interpret Shannon's axioms for a 'measure of choice' in the light of this theory and provide a combinatorial justification for his recurrence formula.

  • Pragmatic truth: Truths that allow you to act in a way that maximises your ability to reproduce. Truths with functional utility.
  • [Set Theory and the Continuum Problem](Set Theory and the Continuum Problem)

Part One's focus on axiomatic set theory features nine chapters that examine problems related to size comparisons between infinite sets, basics of class theory, and natural numbers. Additional topics include author Raymond Smullyan's double induction principle, super induction, ordinal numbers, order isomorphism and transfinite recursion, and the axiom of foundation and cardinals. The six chapters of Part Two address Mostowski-Shepherdson mappings, reflection principles, constructible sets and constructibility, and the continuum hypothesis. The text concludes with a seven-chapter exploration of forcing and independence results. This treatment is noteworthy for its clear explanations of highly technical proofs and its discussions of countability, uncountability, and mathematical induction, which are simultaneously charming for experts and understandable to graduate students of mathematics.

It reminds me of Descarte's argument that even if we were just brains in vats coerced to believe in reality by some evil demon's manipulation, we still "know" something because "cogito ergo sum". A simple counter argument is that there's no reason the evil demon can't also coerce logic. For example, that we are in effect constantly entering into contradiction but are unable to see it by design.

Random Walks and Electric Networks Special Networks Uniform Spanning Trees Branching Processes, Second Moments, and Percolation Isoperimetric Inequalities Percolation on Transitive Graphs The Mass-Transport Principle and Percolation Infinite Electrical Networks and Dirichlet Functions Uniform Spanning Forests Minimal Spanning Forests Limit Theorems for Galton-Watson Processes Escape Rate of Random Walks and Embeddings Random Walks on Groups and Poisson Boundaries Hausdorff Dimension Capacity and Stochastic Processes Random Walks on Galton-Watson Trees

My friend had gone through an elaborate process that basically amounted to performing some other piece of music four minutes and thirty-three seconds long, with a software synthesizer and the volume set to zero. The result was an appropriate-sized file of zeroes - which he compressed with an MP3 compressor. The MP3 file was bit-for-bit identical to one that would have been produced by compressing /dev/zero... but this file was (he claimed) legitimately a recording of 4'33" and the other one wouldn't have been. The difference was the Colour of the bits. He was asserting that the bits in his copy of 433.mp3 had a different Colour from those in a copy of 433.mp3 I might make by means of the /dev/zero procedure, even though the two files would contain exactly the same bits. ... The trouble is, human beings are not in general Colour-blind. The law is not Colour-blind. It makes a difference not only what bits you have, but where they came from. There's a very interesting Web page illustrating the Coloured nature of bits in law on the US Naval Observatory Web site. They provide information on that site about when the Sun rises and sets and so on... but they also provide it under a disclaimer saying that this information is not suitable for use in court. If you need to know when the Sun rose or set for use in a court case, then you need an expert witness - because you don't actually just need the bits that say when the Sun rose. You need those bits to be Coloured with the Colour that allows them to be admissible in court, and the USNO doesn't provide that. It's not just a question of accuracy - we all know perfectly well that the USNO's numbers are good. It's a question of where the numbers came from.

This paper presents a self-replicating, homeostatic phenomenon called M0. M0 runs parasitically on populations of humans. It is remarkable in that although its anatomy is distributed across all phenomenological layers from neurological to paradigmattic, its causal sequences are robust and (once exposed) readily traceable and hence vulnerable to counterattack. The anatomy and lifecycle of the parasite are described, together with several secondary effects which are often of primary importance to the host population. An alternative interpretation of the role of dopamine in controlling mood and awareness is proposed, and how the "security breach" thus exposed is exploited by M0 is shown. A disturbing model of the variability of human consciousness is proposed.

Spaceship Earth (or Spacecraft Earth or Spaceship Planet Earth) is a worldview encouraging everyone on Earth to act as a harmonious crew working toward the greater good. We travel together, passengers on a little space ship, dependent on its vulnerable reserves of air and soil; all committed for our safety to its security and peace; preserved from annihilation only by the care, the work, and, I will say, the love we give our fragile craft. We cannot maintain it half fortunate, half miserable, half confident, half despairing, half slave—to the ancient enemies of man—half free in a liberation of resources undreamed of until this day. No craft, no crew can travel safely with such vast contradictions. On their resolution depends the survival of us all.

A black man says he has accidentally persuaded around 200 white racists to abandon the Klu Klux Klan simply by befriending them. Blues musician Daryl Davis has travelled the US for around three decades, actively seeking out white supremacists as a hobby. In a new documentary, out this month, the 58-year-old can be seen sitting down beside and joking with cloaked members. “It’s a wonderful thing when you see a light bulb pop on in their heads or they call you and tell you they are quitting,” said the author, actor and lecturer. “I never set out to convert anyone in the Klan. I just set out to get an answer to my question: ‘How can you hate me when you don’t even know me’.

This hypothesis proposes that ADHD represents a lack of adaptation of members of hunter-gatherer societies to their transformation into farming societies. Hartmann developed the idea first as a mental model after his own son was diagnosed with ADHD, stating, "It's not hard science, and was never intended to be.". However, more recent molecular and clinical research has given support to a genetic deflection ”theory” of ADHD arising from evolutionary adaptation Hartmann notes that most or all humans were nomadic hunter-gatherers for hundreds of thousands of years, but that this standard gradually changed as agriculture developed in most societies, and more people worldwide became farmers. Over many years, most humans adapted to farming cultures, but Hartmann speculates that people with ADHD retained some of the older hunter characteristics. A key component of the hypothesis is that the proposed "hyperfocus" aspect of ADHD is a gift or benefit under appropriate circumstances. The hypothesis also explains the distractibility factor in ADHD individuals and their short attention span for subject matter that does not interest the individual (which may or may not trigger hyperfocus), along with various other characteristics such as difficulty adhering to social norms, poor planning and organizing ability, distorted sense of time, impatience, attraction to variety or novelty or excitement, and impulsiveness.[citation needed] It is argued that in the hunter-gatherer cultures that preceded farming societies, hunters needed hyperfocus more than gatherers.

How big are gender differences in personality and interests, and how stable are these differences across cultures and over time? To answer these questions, I summarize data from two meta‐analyses and three cross‐cultural studies on gender differences in personality and interests. Results show that gender differences in Big Five personality traits are ‘small’ to ‘moderate,’ with the largest differences occurring for agreeableness and neuroticism (respective ds = 0.40 and 0.34; women higher than men). In contrast, gender differences on the people–things dimension of interests are ‘very large’ (d = 1.18), with women more people‐oriented and less thing‐oriented than men. Gender differences in personality tend to be larger in gender‐egalitarian societies than in gender‐inegalitarian societies, a finding that contradicts social role theory but is consistent with evolutionary, attributional, and social comparison theories. In contrast, gender differences in interests appear to be consistent across cultures and over time, a finding that suggests possible biologic influences.

A married couple was in a car when the wife turned to her husband and asked, "Would you like to stop for a coffee?" "No, thanks," he answered truthfully. So they didn't stop. The result? The wife, who had indeed wanted to stop, became annoyed because she felt her preference had not been considered. The husband, seeing his wife was angry, became frustrated. Why didn't she just say what she wanted? Unfortunately, he failed to see that his wife was asking the question not to get an instant decision, but to begin a negotiation. And the woman didn't realize that when her husband said no, he was just expressing his preference, not making a ruling. When a man and woman interpret the same interchange in such conflicting ways, it's no wonder they can find themselves leveling angry charges of selfishness and obstinacy at each other. As a specialist in linguistics, I have studied how the conversational styles of men and women differ. We cannot lump all men or all women into fixed categories. But the seemingly senseless misunderstandings that haunt our relationships can in part be explained by the different conversational rules by which men and women play.

Silent trade, also called silent barter, dumb barter ("dumb" here used in its old meaning of "mute"), or depot trade, is a method by which traders who cannot speak each other's language can trade without talking. Group A would leave trade goods in a prominent position and signal, by gong, fire, or drum for example, that they had left goods. Group B would then arrive at the spot, examine the goods and deposit their trade goods or money that they wanted to exchange and withdraw. Group A would then return and either accept the trade by taking the goods from Group B or withdraw again leaving Group B to add to or change out items to create an equal value. The trade ends when Group A accepts Group B's offer and removes the offered goods leaving Group B to remove the original goods.

  • Deep trust versus broad trust

we don't have communities like we used to have with deep trust, even the families are not the same anymore. On the other hand I am not afraid to go to neighboring city (or when I was a kid it could be even other part of the city) so someone would come up with "hey you are not from around here, what are you looking for a trouble here son?". We traded deep trust for broad trust. This way price of transactions on bigger scale went down a lot, even if they went up on personal or local level. In the end broad trust is more useful for people because it enables mobility. One can move to a big city and won't be instantly scammed. If we would value deep trust only, there would be no way for people to move out from "dead end" places.

There is a reason why Harvard’s motto is “Veritas”—truth, whereas Yale’s motto is “Lux et veritas”—light and truth. Truth without light is pointless. Knowledge without an aim is at best not useful—and at worst, destructive. ~ The real problem at yale is not free speech

I will try to help with the title question. I think that the real motivation for the Levi-Civita connection comes from looking at surfaces in Euclidean 3-space. Differentate one tangent vector field Y along another X by first extending them to be defined in the ambient space, and then taking the tangential projection of XY, i.e. tangential projection of the Euclidean connection. Levi-Civita discovered that this process is intrinsic, i.e. invariant under isometry of surfaces without carrying along the ambient space, and described precisely by torsion freedom. This was clearly a long and difficult process. Dirac uses this view in his book General Theory of Relativity, and this is how I introduce the Levi-Civita connection in my lectures. I have to agree that there is something missing in the textbook discussions of torsion. I have not found an intuitive understanding of torsion.

In situation X I will do behaviour Y to achieve subgoal Z Value affirmation: Remind yourself of the why.

Consider a set of opaque colored sheets, along with a binary operation of stacking sheets. Then every sheet is a left identity, UNLESS you add a transparent sheet to the set, at which point none of the other sheets are left identities anymore, and only the transparent sheet remains as an identity.

There are two views as to why people stay poor. The equal opportunity view emphasizesthat differences in individual traits like talent or motivation make the poor choose lowproductivity jobs. The poverty traps view emphasizes that access to opportunitiesdepends on initial wealth and hence poor people have no choice but to work in lowproductivity jobs. We test the two views using the random allocation of an asset transferprogram that gave some of the poorest women in Bangladesh access to the same jobopportunities as their wealthier counterparts in the same villages. The data rejectsthe null of equal opportunities. ... Our findings imply that largeone-off transfers that enable people to take on more productive occupations can helpalleviate persistent poverty.

  • SPQR by Mary Beard: is a Roman history more or less with the midpoint as the fall of the Republic and transition to Empire... a very apt piece of history in the current political climate.
  • Anarchy, State, and Utopia by Robert Nozick:

Nozick argues in favor of a minimal state, "limited to the narrow functions of protection against force, theft, fraud, enforcement of contracts, and so on." When a state takes on more responsibilities than these, Nozick argues, rights will be violated. To support the idea of the minimal state, Nozick presents an argument that illustrates how the minimalist state arises naturally from anarchy and how any expansion of state power past this minimalist threshold is unjustified.

Traditional Inuit parenting is incredibly nurturing and tender. If you took all the parenting styles around the world and ranked them by their gentleness, the Inuit approach would likely rank near the top. (They even have a special kiss for babies, where you put your nose against the cheek and sniff the skin.) The culture views scolding — or even speaking to children in an angry voice — as inappropriate, says Lisa Ipeelie, a radio producer and mom who grew up with 12 siblings. "When they're little, it doesn't help to raise your voice," she says. "It will just make your own heart rate go up." Traditionally, the Inuit saw yelling at a small child as demeaning. It's as if the adult is having a tantrum; it's basically stooping to the level of the child, Briggs documented.

The drama triangle is a social model of human interaction – the triangle maps a type of destructive interaction that can occur between people in conflict The triangle of actors in the drama are oppressors, victims and rescuers. The Victim: The Victim's stance is "Poor me!" The Victim feels victimized, oppressed, helpless, hopeless, powerless, ashamed, and seems unable to make decisions, solve problems, take pleasure in life, or achieve insight. The Victim, if not being persecuted, will seek out a Persecutor and also a Rescuer who will save the day but also perpetuate the Victim's negative feelings. The Rescuer: The rescuer's line is "Let me help you." A classic enabler, the Rescuer feels guilty if they don't go to the rescue. Yet their rescuing has negative effects: It keeps the Victim dependent and gives the Victim permission to fail. The rewards derived from this rescue role are that the focus is taken off of the rescuer. When they focus their energy on someone else, it enables them to ignore their own anxiety and issues. This rescue role is also pivotal because their actual primary interest is really an avoidance of their own problems disguised as concern for the victim’s needs. The Persecutor: (a.k.a. Villain): The Persecutor insists, "It's all your fault." The Persecutor is controlling, blaming, critical, oppressive, angry, authoritarian, rigid, and superior.

Most of it is readable to undergraduates. Its target audience, though, is beginning graduate students in mathematics. If not already familiar with hyperbolic geometry, you might want to get an introduction to the subject first. Once with this background, though, you will discover there is another level of understanding of hyperbolic space you never realized was possible. One imagines Thurston able to skateboard around hyperbolic space with the kind of geometric understanding he conveys here.

What both Russell and Conrad were getting at was a simple fact which any historian could confirm: human civilisation is an intensely fragile construction. It is built on little more than belief: belief in the rightness of its values; belief in the strength of its system of law and order; belief in its currency; above all, perhaps, belief in its future. … Once that belief begins to crumble, the collapse of a civilisation may become unstoppable. That civilisations fall, sooner or later, is as much a law of history as gravity is a law of physics. What remains after the fall is a wild mixture of cultural debris, confused and angry people whose certainties have betrayed them, and those forces which were always there, deeper than the foundations of the city walls: the desire to survive and the desire for meaning … What remains after the fall is a wild mixture of cultural debris, confused and angry people whose certainties have betrayed them, and those forces which were always there, deeper than the foundations of the city walls: the desire to survive and the desire for meaning

"Many students, especially those who are poor, intuitively know what the schools do for them. They school them to confuse process and substance. Once these become blurred, a new logic is assumed: the more treatment there is, the better are the results; or, escalation leads to success. The pupil is thereby "schooled" to confuse teaching with learning, grade advancement with education, a diploma with competence, and fluency with the ability to say something new. His imagination is "schooled" to accept service in place of value. Medical treatment is mistaken for health care, social work for the improvement of community life, police protection for safety, military poise for national security, the rat race for productive work. Health, learning, dignity, independence, and creative endeavor are defined as little more than the performance of the institutions which claim to serve these ends, and their improvement is made to depend on allocating more resources to the management of hospitals, schools, and other agencies in question. In these essays, I will show that the institutionalization of values leads inevitably to physical pollution, social polarization, and psychological impotence: three dimensions in a process of global degradation and modernized misery."

Radical monopoly is a concept defined by philosopher and author Ivan Illich in his 1973 book, "Tools for Conviviality," and revisited in his later work, which describes how a technology or service becomes so exceptionally dominant that even with multiple providers, its users are excluded from society without access to the product. His initial example is the effect of cars on societies, where the car itself shaped cities by its needs, so much so that people without cars become excluded from participation in cities. A radical monopoly is when the dominance of one type of product supersedes dominance by any one brand. Social media as a technology in the forms of Facebook/Instagram/Twitter could be seen as a radical monopoly for reputation, as is Linkedin for employment, colleges for education, etc. I think Illich's criticisms of car culture pushed him outside the Overton window of policy making, but his radical monopoly concept is a useful critical tool for reasoning about tech and ethics. A counter argument could use the example that the discovery of fire created a radical monopoly on heat, and therefore it's so general as to be applied arbitrarily to anything you don't like. However, being able to think about the consequences of a new radical monopoly might have on some aspect of human experience is useful for anticipating policy options in response to dynamic technology development.

It sounds like the issue is that the layout isn't spatial. There isn't a 1:1 mapping between place and object. The same place can have multiple objects depending on what tab's selected.

To make an example possibly closer to us, think you're in a car in the urban traffic. Due to one-way streets, metric is not the best way to organize your perception of the space: actually, the proper topology to do that is possibly not Hausdorff (usually, you can't move to A without immediately finding yourself in B, and once you are in B, you are enormously far from A, even if you changed your mind about the opportunity of the movement.)