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versteegen

1,857 karma · joined May 8, 2015

Independent AI researcher (neuro-symbolic NLU, data compression), FLOSS contributor, Generalist & Luddite.

rver017@aucklanduni.ac.nz

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versteegen··on GPT-4.5 or GPT-5 being tested on LMSYS?
The internal state at layer M of token N is available at every following token > N and layer > M via attention heads. Transformed by a matrix but a very direct lookup mechanism. The state after the final attention layer is not addressable in this way, but it immediately becomes the output token which is of course accessible.

Note also that sequential computations such as loops translate nicely to parallel ones, e.g. k layers can search the paths of length k in a graph, if each token represents one node. But since each token can only look backwards, unless you're searching a DAG you'd also have to feed in the graph multiple times so the nodes can see each other. Hmm... that might be a useful LLM prompting technique.

versteegen··on GPT-4.5 or GPT-5 being tested on LMSYS?
> How does it know what the next street or neighbourhood it should traverse in each step without a pathfinding algo?

Because Transformers are 'AI-complete'. Much is made of (decoder-only) transformers being next token predictors which misses the truth that large transformers can "think" before they speak: there are many layers in-between input and output. They can form a primitive high-level plan by a certain layer of a certain token such as the last input token of the prompt, e.g. go from A to B via approximate midpoint C, and then refer back to that on every following token, while expanding upon it with details (A to C via D): their working memory grows with the number of input+output tokens, and with each additional layer they can elaborate details of an earlier representation such as a 'plan'.

However the number of sequential steps of any internal computation (not 'saved' as an output token) is limited by the number of layers. This limit can be worked around by using chain-of-thought, which is why I call them AI-complete.

I write this all hypothetically, not based on mechanistic interpretability experiments.

versteegen··on Google Quantum AI
I can't find mention of it online, but back in 2013 Lockheed Martin purchased a D-Wave machine because they wanted to use it for "AI", which it turned out meant software verification (of fighter jets?) I believe by searching for the possibility of some kind of invalid program state in a large program, which IIRC they couldn't manage to solve with standard solvers. But in that case the number of qubits in a D-Wave machine appears to me far too few for that to be possible, although I don't know the task exactly.

If by "AI" you include operations research (as opposed to statistical machine learning), yes, adiabatic quantum annealing makes sense for certain optimisation problems which you can manage to naturally formulate as a QUBO problem. By 'naturally' I mean it won't blow up the number of variables/qubits, as otherwise a far simpler algorithm on classical computer would be more efficient. I know someone who published QUBO algorithms and ran them on a NASA D-Wave machine, while I myself was using a lot of annealing for optimisation, I didn't want to get involved in that field.

But if you want to do machine learning on a large amount of data using quantum annealing, no, that's terribly badly matched, because the number of physical qubits needed is proportional to the amount of data you want to feed in.

versteegen··on Google Quantum AI
I'm quite taken aback to be viewing a Google website where the 5.8MB images are loading at a crawl, because they're completely unoptimised pngs equal in size to bmps of the same resolution!

Oh hey apparently there are some 26MB of mp4s that didn't load at first, they served a 2.4MB "Mobile" mp4 instead, so it's not all bad.

versteegen··on Human-level few-shot concept induction through minimax entropy learning
Right, but I mean that HMC has parameters to tune and multiples the computation needed per sample produced so it's not clear to me for which problems it's significantly beneficial and with how much tuning. I'd guess it's best where you otherwise don't have a good proposal distribution for Metropolis-Hastings leading to either many rejects or very slow mixing.
versteegen··on Human-level few-shot concept induction through minimax entropy learning
(Whoops, ignore that last line; just fragments of unfinished sentences)
versteegen··on Human-level few-shot concept induction through minimax entropy learning
Sure, there are fruitful parallels. But actually, energy is much 'realer' or more fundamental here than temperature. BTW, those λ_j Lagrangian multipliers can be negative, so don't map onto inverse temperature well. They're more like interaction weights in a Hopfield network.

But there's one setting in which the energy E(x) = Σ_j λ_j H_j(x) really does become a physical (physics-esque) energy: if you sample from the distribution using Hamiltonian Monte Carlo (an MCMC algorithm). Then E(x) is the potential energy of a sample/particle at position x, which is also given a kinetic energy K with the sume E+K held constant as the particle moves about to explore the distribution. It's a cool algorithm but after having used it I'm still not sure how useful it is.

versteegen··on Human-level few-shot concept induction through minimax entropy learning
DNNs are very good at learning features so are a natural fit if you have lots of training data. The main drawback is then you've lost the ability to work with small data. The other drawback is the computational cost of the maxent model on top of it. So you get both the best and the worst of both halves.

So:

input --DNN--> feature vector --minimax_entropy_optimisation--> maxent model --sampling/inference--> output

But minimax entropy learning is just learning a model that matches statistics of a set of features (filters). If you just want to draw a single sample from that model or the maximum likelihood point (e.g. you just want the answer to an IQ question) rather than doing complicated inference (in the DNN era, people have forgotten that "inference" is far more general than classification) you don't actually need the model at all, you can skip learning it, and go straight to computing a result with the desired statistics. This is around 100-1000x faster.

input --DNN--> feature vector --statistics_matching--> output

This is what I mostly did in my PhD work, and there's a famous paper doing this:

A Neural Algorithm of Artistic Style https://arxiv.org/abs/1505.07376

This has a sister paper which is even purer statistics-of-features-matching:

Texture Synthesis Using Convolutional Neural Networks https://arxiv.org/abs/1505.07376

However soon people worked out you can just train a DNN to do the statistics matching directly. Initially, with a fixed target style, and later taking the style as a second input. If the results are acceptable, this is vastly faster at inference time.

input --DNN--> output

Using them in this way would likely mean just replacing the final layer. The original papers on 'style transfer' did this, a DNN plus minimax entropy learning. has been done in texture and image models.

versteegen··on Human-level few-shot concept induction through minimax entropy learning
It's surreal to see this on the front page since I worked on minimax entropy learning for texture modelling (following these authors), then abandoned that line of research because I wanted to work on concept induction and reasoning instead. I'm amazed these authors are still drawing a direct line through 27 years of their papers.

To explain what this is about (not having read the whole paper): it's using 'classical', small sample size statistics to infer relations between very small sets of data such as individual questions of an IQ test. Obviously that's going to give the best possible answer, because that's what classical statistics does. (Well, if you could solve exactly, but with this model you actually can't.) Then it's just a question of having a good prior over possible concepts. In this paper the concepts are hand-defined parametrized features (aka 'filters' in the paper, from the texture modelling lineage), e.g. "families of arithmetic expressions of length from two to six" for the number problems. There will be a lot of details involved in that.

Alternatively, something like a deep neural network trained on vast numbers of generated examples could come to learn what a suitable prior should be by learning the patterns used to generate them. Yet another option is to use a universal prior as in Solomonoff induction, based on representation/coding length.

My conclusion: the theory is good and I'm happy to see this but don't think that you can directly apply this to learning 'concepts' in anything other than IQ tests. The hard part of generalising this is firstly finding the prior over the concepts, and secondly the difficult optimisation step: using MCMC as part of the optimisation is both extremely slow and stochastic in a bad way (unlike SGD) and the reason I abandoned this approach.

versteegen··on Human-level few-shot concept induction through minimax entropy learning
In original FRAME, "learning filters" means selecting filters from a (very small) fixed set. In this paper they add* an additional "bilevel optimization", where they both learn θ_j, the parameters of the filters, and select the filters (indicator variables z_j).

Either way, that learning is the entropy minimisation part.

Maximizing entropy is not really about learning anything, it's about not overfitting. (Although you are correct in that you have to find the Langrange multipliers to correctly combine the filters.) Basically, the desired probability distribution will be constrained only by certain statistics of (the filters you learnt) on the data, and nothing else. For example, you want a model that says "if panel 1 has an N-sided polygon, and panel 2 has an N+1-sided polygon, panel 3 has an N+2-sided polygon", and says nothing about anything else.

* I'm a bit peeved they didn't cite me for extending FRAME by learning the features like that. That was my PhD topic. But let's face it, they probably don't know about my work, or quickly forgot it because the papers were too ugly, and admittedly they've done it in a cleaner way. I had to wrap kludgy iterative feature addition around the feature optimisation step to make it more efficient for image modelling.

versteegen··on Human-level few-shot concept induction through minimax entropy learning
Yes, but...

> some kind of energy

The negenergy (negative energy) here is just the (unnormalised, hence the 1/Z term) log-probability mass or density. Like the logit outputs of classifier.

You shouldn't read anything more into the 'energy'. There is no temperature parameter in these minimax models (although adding one to smooth the model during sampling or learning can be useful, to interpolate between pure noise and the learnt model).

versteegen··on The simple beauty of XOR floating point compression
For anyone wondering, zig-zag encoding is just encoding integers with a sign bit in the LSB instead of twos-complement, hence the name. See also https://news.ycombinator.com/item?id=31382907
versteegen··on The xz sshd backdoor rabbithole goes quite a bit deeper
Whoops, you're right. So this isn't really evidence of anything.

Out of interest I looked up the other commit at that time of day visible in that graph, laying on the arrow. It's [1], which changes the git URL from git.tukaani.org to github.com. Of course, moving the project hosting to github was part of the attack.

[1] https://git.tukaani.org/?p=xz.git;a=commitdiff;h=e1b1a9d6370...

versteegen··on The xz sshd backdoor rabbithole goes quite a bit deeper
The abrupt change in time-of-day when commits occurred supports the theory that Jai Tan is more than one person: https://twitter.com/birchb0y/status/1773871381890924872
versteegen··on XZ backdoor: "It's RCE, not auth bypass, and gated/unreplayable."
Defence in depth. Which of your layers is "more secure" isn't important if none are "perfectly secure", so having an extra (independent) layer such as a VPN is a very good idea.
versteegen··on Models all the way down
Thank you for this comment, you've done a fair better job criticising cultural bias in LLMs than most.

> But how do you create the terabytes of Hindi language content required to make ChatGPT understand Hindi as well as it understands English?

It's wrong to assume that every language needs as much training data as English to match the English performance, since knowledge that isn't language- or culture-specific can transfer, in theory and (what used to be considered amazing) to a large extent in practice, once it understands the language very well. Of course a very large proportion, maybe the majority, of what the largest LLMs learn is cultural, but the actual language learning is only a small fraction: A transformer with only tens of millions of parameters can translate between two languages.

Are you saying ChatGPT (is that GPT 3.5?) is much worse in Hindi when given the same prompt in English and Hindi? I'm disappointed to hear that, I had thought OpenAI had done better at multi-lingual performance than many others.

versteegen··on Stability.ai – Introducing Stable Video 3D
But GP's laptop with 96GB of unified memory would be a M2 Max Macbook or better. The M2 Max has a 4 x 128-bit memory bus (410GB/s) and the M2 Ultra is 8 x 128bit (819GB/s), versus a 4090 at 1008GB/s. But see here for caveats about Mac bandwidth: https://news.ycombinator.com/item?id=38811290
versteegen··on Stability.ai – Introducing Stable Video 3D
First Intel and then AMD funded a wrapper, yes. Unfortunately the new version supports AMD but no longer Intel.

https://github.com/vosen/ZLUDA

That's a binary level wrapper. Of course there's also ROCm HIP at the source level, and many other things, such as SYCL

versteegen··on Varda Capsule Reentry – Five Minutes from LEO to Earth [video]
You are correct (aside from the s/ME/M/ typo), but the snark isn't needed.
versteegen··on Nvidia Announces Financial Results for Fourth Quarter and Fiscal 2024
Their gross margin for Q4 is 76% (was 63% a year ago).
versteegen··on Vesuvius Challenge 2023 Grand Prize awarded: we can read the first scroll
The ink is carbon-based, without iron. However there's plenty of contrast when viewed in infrared.
versteegen··on How is a binary executable organized? Let's explore it (2014)
It's even quite interesting to run strings on programs I wrote and I do it regularly. For example it can be faster to get the version string from an .exe using strings if you know what to grep for than to run "wine program.exe --version".
versteegen··on How is a binary executable organized? Let's explore it (2014)
Put the offset at the end! Famously, the table of contents of a .zip file are the end rather than the beginning, which has many useful properties (such as being able to patch the contents by only appending to an existing file). And you can concatenate an executable and a .zip and get a file which is both.
versteegen··on Starlink's laser system is beaming 42 petabytes of data per day
Been quite a lot of discussion of both of those things in this thread!
versteegen··on Starlink's laser system is beaming 42 petabytes of data per day
> the odds of a rocket hitting a satellite on its way up are incredibly low

Aside, but it's not left to chance. They only launch when there's a gap in the space traffic.

versteegen··on Google TPU v5p beats Nvidia H100
nabla9 said "one Grace Hopper" not "one GH200 pod".

Actually, DGX GH200 seem to come in different sizes, something that I can't find clearly stated on Nvidia's website, but what I do see are entirely inconsistent specs. I'm thinking they've changed it a few times.

https://developer.nvidia.com/blog/announcing-nvidia-dgx-gh20... describes the DGX GH200 as:

-256 NVIDIA Grace Hopper Superchips (1 CPU + 1 GPU)

-each Grace CPU has 480 GB LPDDR5 CPU memory

-each H100 GPU has 96 GB of HBM3

-each GPU can access all of the CPU and GPU memory in the whole system (144TB), at 900 GBps

At https://www.nvidia.com/en-us/data-center/dgx-gh200/ (linked to from the DGX page from the website) which has a Datasheet pdf they say the DGX GH200 has:

-32 NVIDIA Grace Hopper Superchips (1 CPU + 1 GPU)

-each Grace CPU has 72 "ARM Neoverse V2 Cores with SVE2 4X 128"

-each GPU can access "19.5TB" shared memory

-that's 624GB per superchip, which is weird. I expect it's actually 96GiB HBM3 + 512GiB LPDDR, a total of 19456GiB = 19.0TiB

And other people have found completely different specs elsewhere on the website!

versteegen··on Dangerous chemicals found in recycled plastics, making them unsafe for use
Aluminium certainly, but glass is not clear cut. A quick web search leaves me thinking it depends, not just on whether you measure energy, greenhouse gases, or cost (versus cost of disposal if not recycled), but also all of those vary between countries.

Yes, economics of recycling plastic are very bad, I wonder how high the cost of landfill would need to increase to make it more expensive than recycling.

versteegen··on Dangerous chemicals found in recycled plastics, making them unsafe for use
> Polystyrene is relatively easy to depolymerize with enzymes, catalysts and moderate amounts of heat

Wow. The paper from 2022 so surely noone is using this process yet, but are there any plans to? Any idea if it's practical? For expanded polystyrene?

versteegen··on FAQ on Leaving Google
Yeah, when I first looked at the shocking source code for bionic (Android's libc) to figure out why my code wasn't working I couldn't believe it was written by Google. It wasn't really. (Nor did they (initially) borrow from any of the high-quality open source libcs out there.)
versteegen··on Show HN: A minimal working Rust / SDL2 / WASM browser game
Half true. Emscripten implements (much of) the SDL 1.2 (and also SDL_mixer 1.2) API in Javascript here: https://github.com/emscripten-core/emscripten/blob/main/src/.... On the other hand SDL 2 (and SDL_mixer 2) are proper ports (which you linked to).

So there's quite a size penalty to using SDL 2 rather than SDL 1.2, but the reimplemented SDL[_mixer] 1.2 is incomplete and differs from official.

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