trentmkelly/LessWrong-43k huggingface dataset:
Pract: A Guessing and Testing Game
by  — 2009-07-31T09:13:47.353Z

Here’s a game that you can play for real against a human opponent. If the administrators don’t mind, you can play it right here in the comments.

The game is called Pract.

Rules

Pract is played using finite sequences of integers, called “sequences.”

To start, each player chooses a well-defined infinite set of sequences, such that every sequence is either demonstrably in or demonstrably out of the set. The game ends when one player guesses the other’s set.1

Once they have picked their sets, the players take turns.

Definitions

A player specifies a sequence by writing each integer, in order, in decimal.

A sequence’s classification relative to a set is a statement of whether the sequence is in or out of the set.

A player classifies a sequence by writing the sequence’s classification relative to that player’s chosen set.

The current player is the player whose turn it currently is.

A player’s final score is the number of guesses made by that player plus the length of that player’s statement (at the end of the game) of the definition of his or her own set.

Gameplay

On each turn, the current player may either:

Try to guess the other player’s set, in which case the other player indicates whether the guess was correct or not. Or,

Specify a sequence, in which case both players classify that sequence.

If, during the previous turn, the other player made an incorrect guess of the current player’s set, the specified sequence must have an opposite classification relative to the actual set than it does relative to the guessed set.

If the other player instead specified a sequence, the two sequences (the one specified by the current player this turn and the one specified the other player on the previous turn) must have opposite classifications relative to the current player’s set.

When a correct guess is made, each player states the definition of his or her own set. The player who guessed correctly makes this statement second. Then the game ends.

Winning and Losing

If the player who guessed correctly has a lower final score than the other player, the player who guessed correctly wins and the other player loses. Otherwise, both players lose.

If a player withdraws from the game during his or her own turn, both players lose.2

Statement lengths affect final scores, so language, notation, and encoding are...
The Hero With A Thousand Chances
by Eliezer Yudkowsky — 2009-07-31T04:25:28.630Z

"Allow me to make sure I have this straight," the hero said. "I've been untimely ripped from my home world to fight unspeakable horrors, and you say I'm here because I'm lucky?"

Aerhien dipped her eyelashes in elegant acknowledgment; and quietly to herself, she thought: Thirty-seven. Thirty-seven heroes who'd said just that, more or less, on arrival.

Not a sign of the thought showed on her outward face, where the hero could see, or the other council members of the Eerionnath take note. Over the centuries since her accidental immortality she'd built a reputation for serenity, more or less because it seemed to be expected.

"There are kinds and kinds of luck," Aerhien said serenely. "Not every person desires their personal happiness above all else. Those who are lucky in aiding others, those whose luck is great in succor and in rescue, these ones are not always happy themselves. You are here, hero, because you have a hero's luck. The boy whose dusty heirloom sword proves to be magical. The peasant girl who finds herself the heir to a great kingdom. Those who discover, in time of sudden stress, an untrained wild magic within themselves. Success born not of learning, not of skill, not of determination, but unplanned coincidence and fortunes of birth: That is a hero's luck."

"Gosh," said the hero after a long, awkward pause, "thanks for the compliment."

"It is not a compliment," Aerhien said, "but this is: that you have taken good advantage of your luck. Our enemy does not speak, we do not know if there is any aliveness in it to think; but it learns, or seems to learn. We have never won against it using the same trick twice. It is rare now that a hero succeeds in conceiving a genuinely new trick, for we have fought this shadow long under our sun. For this reason we have taken to summoning heroes from distant dimensions with other modes of thought; sometimes one such knows a truly new technique, and at least they fight differently. But far more often, hero, the hero wins by luck."

"Huh," said the hero. He frowned; more in thought, it seemed, than in displeasure. "How... very odd. I wonder why that is. What kind of enemy can be defeated only by luck?"

"A nameless enemy and null," said Aerhien. "Structureless and empty, horrible and dark, the most te...
The Obesity Myth
by Matt_Simpson — 2009-07-30T00:12:06.160Z

Related To: The Unfinished Mystery of the Shangri-La Diet and Missed Distinctions

Megan McArdles blogs an interview with Paul Campos, author of The Obesity Myth. I'll let anyone who is interest read the whole thing, but here's some interesting excerpts:

I mean, there's no better established empirical proposition in medical science that we don't know how to make people thinner. But apparently this proposition is too disturbing to consider, even though it's about as well established as that cigarettes cause lung cancer. So all these proposals about improving public health by making people thinner are completely crazy. They are as non-sensical as anything being proposed by public officials in our culture right now, which is saying something.

It's conceivable that through some massive policy interventions you might be able to reduce the population's average BMI from 27 to 25 or something like that. But what would be the point? There aren't any health differences to speak of for people between BMIs of about 20 and 35, so undertaking the public health equivalent of the Apollo program to reduce the populace's average BMI by a unit or two (and again I will emphasize that we don't actually know if we could do even that) is an incredible waste of public health resources

and

Megan: An economist recently pointed out that we don't encourage people to move to the country, even though rural people live more than three years longer than urban people, and the diffefence in their healthy life expectancy is even more outsized. Nor do we encourage people to find Jesus or get married. We target "unhealthy" behaviors that are already stigmatized.
Paul: Right, as Mary Douglas the anthropologist has pointed out, we focus on risks not on the basis of "rational" cost-benefit analysis, but because of the symbolic work focusing on those risks does -- most particularly signalling disapproval of certain groups and behaviors. In this culture fatness is a metaphor for poverty, lack of self-control, and other stuff that freaks out the new Puritans all across the ideological spectrum, which is why the war on fat is so ferocious -- it appeals very strongly to both the right and the left, for related if different reasons.
Information cascades in scientific practice
by Richard_Kennaway — 2009-07-29T12:08:31.135Z

Here's an interesting recent paper in the British Medical Journal: "How citation distortions create unfounded authority: analysis of a citation network". (I don't know if this is freely accessible, but the abstract should be.)

From the paper:

"Objective To understand belief in a specific scientific claim by studying the pattern of citations among papers stating it."

"Conclusion Citation is both an impartial scholarly method and a powerful form of social communication. Through distortions in its social use that include bias, amplification, and invention, citation can be used to generate information cascades resulting in unfounded authority of claims. Construction and analysis of a claim specific citation network may clarify the nature of a published belief system and expose distorted methods of social citation."

It also includes a list of specific ways in which citations were found to amplify or invent evidence.
Thomas C. Schelling's "Strategy of Conflict"
by cousin_it — 2009-07-28T16:08:16.244Z

It's an old book, I know, and one that many of us have already read. But if you haven't, you should.

If there's anything in the world that deserves to be called a martial art of rationality, this book is the closest approximation yet. Forget rationalist Judo: this is rationalist eye-gouging, rationalist gang warfare, rationalist nuclear deterrence. Techniques that let you win, but you don't want to look in the mirror afterward.

Imagine you and I have been separately parachuted into an unknown mountainous area. We both have maps and radios, and we know our own positions, but don't know each other's positions. The task is to rendezvous. Normally we'd coordinate by radio and pick a suitable meeting point, but this time you got lucky. So lucky in fact that I want to strangle you: upon landing you discovered that your radio is broken. It can transmit but not receive.

Two days of rock-climbing and stream-crossing later, tired and dirty, I arrive at the hill where you've been sitting all this time smugly enjoying your lack of information.

And after we split the prize and cash our checks I learn that you broke the radio on purpose.

Schelling's book walks you through numerous conflict situations where an unintuitive and often self-limiting move helps you win, slowly building up to the topic of nuclear deterrence between the US and the Soviets. And it's not idle speculation either: the author worked at the White House at the dawn of the Cold War and his theories eventually found wide military application in deterrence and arms control. Here's a selection of quotes to give you a flavor: the whole book is like this, except interspersed with game theory math.

The use of a professional collecting agency by a business firm for the collection of debts is a means of achieving unilateral rather than bilateral communication with its debtors and of being therefore unavailable to hear pleas or threats from the debtors.

A sufficiently severe and certain penalty on the payment of blackmail can protect a potential victim.

One may have to pay the bribed voter if the election is won, not on how he voted.

I can block your car in the road by placing my car in your way; my deterrent threat is passive, the decision to collide is up to you. If you, however, find me in your way and threaten to collide unless I move, you enjoy no such advantage: the decision to collide is

...
The Trolley Problem in popular culture: Torchwood Series 3
by botogol — 2009-07-27T22:46:57.377Z

It's just possible that some lesswrong readers may be unfamiliar with Torchwood: It's a British sci-fi TV series, a spin-off from the more famous, and very long-running cult show Dr Who.

Two weeks ago Torchwood Series 3 aired. It took the form of a single story arc, over five days, shown in five parts on consecutive nights. What hopefully makes it interesting to rationalist lesswrong readers who are not (yet) Whovians was not only the space monsters (1) but also the show's determined and methodical exploration of an iterated Trolley Problem: in a process familiar to seasoned thought-experimenters the characters were tested with a dilemma followed by a succession of variations of increasing complexity, with their choices ascertained and the implications discussed and reckoned with.

An hypothetical, iterated rationalist dilemma... with space monsters... and monsters a great deal more scary - and messier - than Omega - what's not to like?

So, on the off chance that you missed it, and as a summer diversion from more academic lesswrong fare, I thought a brief description of how a familiar dilemma was handled on popular British TV this month, might be of passing interest (warning: spoilers follow)

The details of the scenario need not concern us too much here (and readers are warned not too expend too much mental energy exploring the various implausibilities, for want of distraction) but suffice to say that the 456, a race of evil aliens, landed on Earth and demanded that a certain number of children be turned over to them to suffer a horrible fate-worse-than-death or else we face the familiar prospects of all out attack and the likely destruction of mankind.

Resistance, it almost goes without saying, was futile.

The problems faced by the team could be roughly sorted into some themes

The Numbers dilemma - is it worth sacrificing any amount of children to save the rest?

first (2) the 456 demand just 35 children

but later they demand 10% of the child population.

The Quality dilemma: does it make any difference which children?

what if, say, the sacrificed children are solely those whom nobody will miss?

The choice dilemma: how should the sacrifical cohort be chosen?

are there any criteria that are fairer, or more rational, than the obvious lottery?

other than 'fairness' what other criteria can you think of for selecting the victims?

The limits of human rat...
Religion and conservation of evidence
by PhilGoetz — 2009-07-27T17:05:33.099Z

Stereotypically, people say that religion is the "opiate of the masses", and expect poor people to be religious, because it gives them solace for their problems.

But most of the religious people I've known are relatively wealthy, Mercedes-driving people, to whom Christianity gives the comfort of believing that their wealth is the result of God's plan, and of their own virtue, rather than accident.

And the people in-between rich and poor tend to deviate less from accepted social behavior, and thus are more likely to be religious.

So every possible economic status increases the priors of being religious. Wait, that can't be right.
Bayesian Utility: Representing Preference by Probability Measures
by Vladimir_Nesov — 2009-07-27T14:28:55.021Z

This is a simple transformation of standard expected utility formula that I found conceptually interesting.

For simplicity, let's consider a finite discrete probability space with non-zero probability at each point p(x), and a utility function u(x) defined on its sample space. Expected utility of an event A (set of the points of the sample space) is the average value of utility function weighted by probability over the event, and is written as

EU(A)=∑x∈Ap(x)⋅u(x)∑x∈Ap(x)

Expected utility is a way of comparing events (sets of possible outcomes) that correspond to, for example, available actions. Event A is said to be preferable to event B when EU(A)>EU(B). Preference relation doesn't change when utility function is transformed by positive affine transformations. Since the sample space is assumed finite, we can assume without loss of generality that for all x, u(x)>0. Such utility function can be additionally rescaled so that for all sample space

∑xp(x)⋅u(x)=1

Now, if we define

q(x)=p(x)⋅u(x)

the expected utility can be rewritten as

EU(A)=∑x∈Aq(x)∑x∈Ap(x)

or

EU(A)=Q(A)P(A)

Here, P and Q are two probability measures. It's easy to see that this form of expected utility formula has the same expressive power, so preference relation can be defined directly by a pair of probability measures on the same sample space, instead of using a utility function.

Expected utility written in this form only uses probability of the whole event in both measures, without looking at the individual points. I tentatively call measure Q "shouldness", together with P being "probability". Conceptual advantage of this form is that probability and utility are now on equal footing, and it's possible to work with both of them using the familiar Bayesian updating, in exactly the same way. To compute expected utility of an event given additional information, just use the posterior shouldness and probability:

EU(A|B)=Q(A|B)P(A|B)

If events are drawn as points (vectors) in (P,Q) coordinates, expected utility is monotone on the polar angle of the vectors. Since coordinates show measures of events, a vector depicting a union of nonintersecting events is equal to the sum of vectors depicting these events:

(P(A∪B),Q(A∪B))=(P(A),Q(A))+(P(B),Q(B)), A∩B=∅

This allows to graphically see some of the structure of simple sigma-algebras of the sample space together with a preference relation defined by a pair of...
The Second Best
by Wei Dai — 2009-07-26T22:58:42.349Z

In economics, the ideal, or first best, outcome for an economy is a Pareto-efficient one, meaning one in which no market participant can be made better off without someone else made worse off. But it can only occur under the conditions of “Perfect Competition” in all markets, which never occurs in reality. And when it is impossible to achieve Perfect Competition due to some unavoidable market failures, to obtain the second best (i.e., best given the constraints) outcome may involve further distorting markets away from Perfect Competition.

To me, perhaps because it was the first such result that I learned, “second best” has come to stand generally for the yawning gap between individual rationality and group rationality. But similar results abound. For example, in Social Choice Theory, Arrow's Impossibility Theorem states that there is no voting method that satisfies a certain set of axioms, which are usually called fairness axioms, but can perhaps be better viewed as group rationality axioms. In Industrial Organization, a duopoly can best maximize profits by colluding to raise prices. In Contract Theory, rational individuals use up resources to send signals that do not contribute to social welfare. In Public Choice Theory, special interest groups successfully lobby the government to implement inefficient policies that benefit them at the expense of the general public (and each other).

On an individual level, the fact that individual and group rationality rarely coincide means that often, to pursue one is to give up the other. For example, if you’ve never cheated on your taxes, or slacked off at work, or lost a mutually beneficial deal because you bargained too hard, or failed to inform yourself about a political candidate before you voted, or tried to monopolize a market, or annoyed your spouse, or annoyed your neighbor, or gossiped maliciously about a rival, or sounded more confident about an argument than you were, or took offense to a truth, or [insert your own here], then you probably haven't been individually rational.

"But, I'm an altruist," you might claim, "my only goal is societal well-being." Well, unless everyone you deal with is also an altruist, and with the exact same utility function, the above still applies, although perhaps to a lesser extent. You should still cheat on your taxes because the government won't spend your money as effectively as yo...
Bayesian Flame
by cousin_it — 2009-07-26T16:49:51.120Z

There once lived a great man named E.T. Jaynes. He knew that Bayesian inference is the only way to do statistics logically and consistently, standing on the shoulders of misunderstood giants Laplace and Gibbs. On numerous occasions he vanquished traditional "frequentist" statisticians with his superior math, demonstrating to anyone with half a brain how the Bayesian way gives faster and more correct results in each example. The weight of evidence falls so heavily on one side that it makes no sense to argue anymore. The fight is over. Bayes wins. The universe runs on Bayes-structure.

Or at least that's what you believe if you learned this stuff from Overcoming Bias.

Like I was until two days ago, when Cyan hit me over the head with something utterly incomprehensible. I suddenly had to go out and understand this stuff, not just believe it. (The original intention, if I remember it correctly, was to impress you all by pulling a Jaynes.) Now I've come back and intend to provoke a full-on flame war on the topic. Because if we can have thoughtful flame wars about gender but not math, we're a bad community. Bad, bad community.

If you're like me two days ago, you kinda "understand" what Bayesians do: assume a prior probability distribution over hypotheses, use evidence to morph it into a posterior distribution over same, and bless the resulting numbers as your "degrees of belief". But chances are that you have a very vague idea of what frequentists do, apart from deriving half-assed results with their ad hoc tools.

Well, here's the ultra-short version: frequentist statistics is the art of drawing true conclusions about the real world instead of assuming prior degrees of belief and coherently adjusting them to avoid Dutch books.

And here's an ultra-short example of what frequentists can do: estimate 100 independent unknown parameters from 100 different sample data sets and have 90 of the estimates turn out to be true to fact afterward. Like, fo'real. Always 90% in the long run, truly, irrevocably and forever. No Bayesian method known today can reliably do the same: the outcome will depend on the priors you assume for each parameter. I don't believe you're going to get lucky with all 100. And even if I believed you a priori (ahem) that don't make it true.

(That's what Jaynes did to achieve his awesome victories: use trained intuition to pick good priors by hand on a per-sam...
Five Stages of Idolatry
by  — 2009-07-25T18:16:54.737Z

We all have heroes or idols, people we look up to and turn to, in one form or another, for guidance or wisdom. Over the years, I've noticed that my feelings towards those I've idolized tend to follow a predictable pattern. The following is the extraction of this pattern.

Stage 1: Exposure - you're exposed to the idol through some channel. Maybe something you read, or someone you know, or simply by chance. You begin to learn about them, and you become intrigued. If it's an author, maybe you pick up one of his books. If it's a group, maybe you check out their website. You begin to gradually absorb what the idol is offering. They don't actually become an idol though, until...

Stage 2: Resonance - after enough exposure, what the idol offers begins to strike a chord with you. You go on to ravenously consume everything related to it. You track down every one of the authors publications, or spend hours staring at all of an artists' paintings. As far as I can tell what's important here isn't actually the content of what the idol offers, but that feeling of resonance it engenders.

Step 3: Incorporation - the idol has become one of the lenses through which you view the world. Everyone and everything is compared to the idol, and everyone invariable comes up short (raise your hand if you've ever thought about someone "Well, they're pretty smart, but not as smart as Eliezer"). You change your lifestyle to be more like them, to think more like them. It's as if they have all aspects of life figured out, and you follow along in the hopes that you will reach their same understanding. The most fervent support of the idol lies here.

Step 4: Backlash - you start to realize that the idol does not, in fact, provide the answers to all of life's questions. That they might be wrong about some things, or that their specific offering does not apply to all life's situations. You've changed yourself to emulate the idol, and you realize that perhaps not all those changes were for the better. Paradoxically, the blame for this gets placed on the idol instead of you. Feelings toward it shift from worship to antipathy.

Step 5: Re-incorporation - after enough time has been spent hating the idol, you come to realize, if only subconsciously, that the fault lies not in the idol, but in your worship. The cycle ends with a more reserved incorporation of what the idol does offer, along with the rea

...