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canjobear

5,303 karma · joined October 24, 2013

All things physical are information-theoretic in origin.

Web http://socsci.uci.edu/~rfutrell/ Twitter @rljfutrell

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canjobear··on A new type of neural network is more interpretable
Not hard to understand. The visualization is more or less the computation graph that PyTorch builds up. And the einsum code is even clearer.

There’s definitely a practice effect though. I know people who aren’t used to it will have their eyes glaze over when they read einsum notation.

canjobear··on The non-Riemannian nature of perceptual color space (2022)
> Any color perception that we can register is a combination of these three signals. Hence a three-dimensional space.

Only approximately. In the linked article you can see that the color gamut is a horseshoe shape that cannot be fully spanned by a triangle. So there are color percepts such as responses to pure wavelengths that can’t be reproduced as combinations of real primaries. You could invent imaginary primary colors to make it work, hence the XYZ color space.

In any case, the whole point of TFA is that a space is not an adequate characterization of color percepts, because there is no Riemannian geometry that matches the psychophysical data.

canjobear··on Fast Multidimensional Matrix Multiplication on CPU from Scratch (2022)
Quasi-related: Do BLAS libraries ever actually implement Strassen's Algorithm?
canjobear··on Bayesian Statistics: The three cultures
You’re right that a particular claim like p(X=x)=a can’t be falsified in general. But whole functions p can be compared and we can say one fits the data better than another.

For example, say Nate Silver and Andrew Gelman both publish probabilities for the outcomes of all the races in the election in November. After the election results are in, we can’t say any individual probability was right or wrong. But we will be able to say whether Nate Silver or Andrew Gelman was more accurate.

canjobear··on Zulip 9.0: Organized chat for distributed teams
What is deceptive here? This seems like a reasonable way to present the information.
canjobear··on What Is Entropy?
I think this gets into unanswerable metaphysical questions about when we can say mathematical objects, propositions, etc. really exist.

But I think if we take the view that it's not a random variable until we query it, that makes it awkward to talk about how GPT-2 (and similar models) is trained. No one ever draws samples from the model during training, but the whole justification for the cross-entropy-minimizing training procedure is based on thinking about the model as a random variable.

canjobear··on What Is Entropy?
Cross entropy lets you compare two probability distributions. One way you can apply it is to let the distribution p represent "reality" (from which you can draw many samples, but whose numerical value you might not know) and to let q represent "beliefs" (whose numerical value is given by a model). Then by finding q to minimize cross-entropy H[p, q] you can move q closer to reality.

You can apply it other ways. There are lots of interpretations and uses for these concepts. Here's a cool blog post if you want to find out more: https://blog.alexalemi.com/kl-is-all-you-need.html

canjobear··on What Is Entropy?
This kind of thinking will lead you to ideas like algorithmic probability, where distributions are defined using universal Turing machines that could model anything.
canjobear··on What Is Entropy?
You might have some probability distribution in your head for what will come out of GPT-2 on your machine at a certain time, based on your knowledge of the random seed. But that is not the GPT-2 probability distribution, which is objectively defined by model weights that you can download, and which does not correspond to anyone’s beliefs.
canjobear··on What Is Entropy?
Would you say that all claims about the world are subjective, because they have to be based on someone’s observations?

For example my cat weighs 13 pounds. That seems objective, in the sense that if two people disagree, only one can be right. But the claim is based on my observations. I think your logic leads us to deny that anything is objective.

canjobear··on What Is Entropy?
What's often lost in the discussions about whether entropy is subjective or objective is that, if you dig a little deeper, information theory gives you powerful tools for relating the objective and the subjective.

Consider cross entropy of two distributions H[p, q] = -Σ p_i log q_i. For example maybe p is the real frequency distribution over outcomes from rolling some dice, and q is your belief distribution. You can see the p_i as representing the objective probabilities (sampled by actually rolling the dice) and the q_i as your subjective probabilities. The cross entropy is measuring something like how surprised you are on average when you observe an outcome.

The interesting thing is that H[p, p] <= H[p, q], which means that if your belief distribution is wrong, your cross entropy will be higher than it would be if you had the right beliefs, q=p. This is guaranteed by the concavity of the logarithm. This gives you a way to compare beliefs: whichever q gets the lowest H[p,q] is closer to the truth.

You can even break cross entropy into two parts, corresponding to two kinds of uncertainty: H[p, q] = H[p] + D[q||p]. The first term is the entropy of p and it is the aleatoric uncertainty, the inherent randomness in the phenomenon you are trying to model. The second term is KL divergence and it tells you how much additional uncertainty you have as the result of having wrong beliefs, which you could call epistemic uncertainty.

canjobear··on What Is Entropy?
Some probability distributions are objective. The probability that my random number generator gives me a certain number is given by a certain formula. Describing it with another distribution would be wrong.

Another example, if you have an electron in a superposition of half spin-up and half spin-down, then the probability to measure up is objectively 50%.

Another example, GPT-2 is a probability distribution on sequences of integers. You can download this probability distribution. It doesn't represent anyone's beliefs. The distribution has a certain entropy. That entropy is an objective property of the distribution.

canjobear··on What Is Entropy?
Entropy in physics is usually the Shannon entropy of the probability distribution over system microstates given known temperature and pressure. If the system is in equilibrium then this is objective.
canjobear··on What is the significance of the character "j" at the end of a Roman Numeral? (2013)
Not only the romanization, also the capital form in German is SS.

The ß sticks around in German because it prevents some ambiguities. For example Busse and Buße are different words with different pronunciations.

Basically German orthography backed itself into a corner because of two rules: a vowel before a doubled consonant is short, and an s before a vowel is pronounced /z/. This leaves you with no clear way to write a long vowel followed by an /s/ sound followed by a vowel: VssV would make the first vowel short, and VsV would keep the first vowel long but the consonant would be pronounced as /z/. The ß solves this problem.

canjobear··on Five common English words we don't know the origins of–including 'boy' and 'dog'
Noob < newbie < newborn < Germanic new + Germanic born.

It's hard to find a word that is a truly original coinage not based on any existing words.

canjobear··on A Dramatic Reading: I Will Fucking Piledrive You If You Mention AI Again
Reminds me of the classic “MongoDB is web scale” https://youtu.be/b2F-DItXtZs
canjobear··on Tao Te Ching translated by Ursula Le Guin (1997)
Interestingly the 常 was originally 恒, meaning “constant,” in the oldest manuscripts. It got changed to 常 because it was taboo to write any character appearing in the given name of an Enperor, and Emperor Wen of Han had the given name 恒.
canjobear··on Tao Te Ching translated by Ursula Le Guin (1997)
The really impossible thing to translate into English here is that 道 was also the verb “to say.” So 道可道 is a pun that could mean “the way that can be trod” or “the way that can be said.”
canjobear··on Tao Te Ching translated by Ursula Le Guin (1997)
It was a bona fide spoken language at the time the Daodejing was written. Likely sounding very little like modern Chinese.
canjobear··on Trilobites killed by volcanic ash
The website itself is like a fossil.
canjobear··on Diagraming sentences in the 19th century
As a Southerner who would definitely say "I might could…", I would never say “I didn’t necessarily could speak it well”. That’s not how double modals work. (“I used to could…” seems marginally ok to me though.)

Also the “needs fixed” thing is not a Southern dialect property, I associate it more with like Pittsburgh.

canjobear··on I've stopped using box plots (2021)
It looks like a spike, not a bell.
canjobear··on Aphantasia: I can not picture things in my mind
The point isn’t to rigorously define “visualize” or “imagine”—we will probably never be able to do this. The point is to use a verbal prompt to elicit a mental experience and then to try to probe that experience.

> A triangle doesn't have to be filled with a color to be a triangle. Why would you imagine it with any color in it in the first place, not just a wireframe, being transparent inside?

That’s just it: when I imagine a triangle, it is a definite image with a definite color. The visual details like color come automatically for me. I cannot imagine it in the more abstract way you are describing. If it’s a wireframe, the wireframe is gray. It’s always a full, colorful, 3d scene, perhaps vague but definitely with visual detail.

canjobear··on Aphantasia: I can not picture things in my mind
If I say "imagine a triangle" and ask you what color it is, why would it have a color if there is no image there? I didn't ask you to imagine a red triangle. Only a triangle. The only way it logically gets a color is if you are visualizing it.
canjobear··on Aphantasia: I can not picture things in my mind
If you’re looking for objective measures, aphantasia correlates inversely with objective measures of visual memory.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7856239/

But you can also imagine tests based on introspection which are better than just straight up asking how vivid your mental imagery is.

For example: imagine a triangle. What color is it?

For a true aphantasiac, this question is meaningless. It has no color because it’s just an abstract concept. For me it is a white outline on a black background, very vividly.

canjobear··on Rotation curves: still flat after a million light-years
What would cause the large majority of a scientific field to fall for propaganda? If MOND is predictively superior then why is it not accepted?
canjobear··on Rotation curves: still flat after a million light-years
https://en.m.wikipedia.org/wiki/Tensor%E2%80%93vector%E2%80%...

The extra components would have energy and function as Dark Matter.

canjobear··on Japanese words and names sound African (2022)
I’d say the situation is worse than “doubtful”—-There was never any really good evidence for Ural-Altaic.

Altaic is a little more complicated, but whatever it is, it doesn’t seem to be a linguistic family tree in the same way that Indo-European is.

canjobear··on Chinese yuan becomes Russia's main foreign currency, replacing dollar and euro
That’s literally “Vladivostok” in Chinese.
canjobear··on The illusion of state in state-space models
Languages do in fact have similar distributional structure, so that it is possible to learn how to translate words without supervision: https://arxiv.org/abs/2203.04863

In principle languages are arbitrary, but in practice they’re describing the same world and the same concepts end up being useful.

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