jsenn

This looks cool, but I wonder how well their trained compiler generalizes to new task families. They trained on 29 specific types of tasks, with 800 sub tasks and many rephrasings of each one (the specs). They hold out some specs for validation, but don’t seem to have held out a full task family and maybe not even full sub tasks?

If the compiler can’t generalize well to unseen tasks then it’s effectively acting as a fancy router to one of 29/800 predefined LoRAs.

Their demo is almost unbelievably fast, but as I understand it, the limitation of Taalas's strategy is KV-cache. This grows with context length, so either needs to be stored in SRAM (small) or streamed in (slow). Even for a tiny model like the Llama 8B they have in their demo, the KV cache will be ~64kb per token at 8-bit quantization, so at a 1,000-token sequence length you are already at 64MB of SRAM for a single user. This is probably why their demo only lets you generate 1,000 tokens: they can't go beyond that without slowing down inference.

So I'm curious what their strategy is. It seems to me that the options are: 1. Target smaller usecases that can live with a tiny context window 2. Use huge amounts of SRAM (at which point they look like Groq or Cerebras) 3. Make it up with extreme KV-cache compression/quantization 4. Run linear-attention/sliding window attention models

Other commenters have mentioned robotics as a potential application, which sounds interesting.

isn't the verification code going to be sloppy as well

The beauty of formal methods is it doesn't matter if your proof is sloppy. As long as it passes verification, it is correct. And unlike in pure math, the proof that a software system is correct is usually a huge mess of special cases, loop invariants, proofs by induction, and boilerplate that requires a large amount of human labour while providing no insight.

Proofs are also brittle: a tiny change in the code can force you to throw your proof away and start from scratch.

To me, the exciting thing about formal methods in the LLM era is it allows humans to offload the difficult and tedious work of writing proofs to a computer. Taken to an extreme, the human could live entirely in the world of a formal specification, and the LLM could generate 100% of the code. The code may be a mess, but if the system proves it satisfies the spec then it can't be wrong.

The article you are responding to showed that a strange LLM behaviour was caused by a training signal that was explicitly designed to produce that type of behaviour. They were able to isolate it, clearly demonstrate what happened, and roll out a mitigation using a mechanism they engineered for exactly this type of thing (the developer prompt). That doesn’t sound like sorcery to me. If anything I’m surprised you can so easily engineer these things!

Is this parlour trick so different from useful tasks like “implement this feature while following the naming conventions of my project”?

Section 2.6 gives the hidden state size per token, which, on first read, is strictly larger than the hidden state in normal attention

This is where you’ve gone off track. The “hidden state” for their model is a fixed size thing, like in an RNN, not per token. For a transformer, the “hidden state” is called the KV cache, and it grows with sequence length. This is why their method is linear not quadratic.

The Taylor Series they derive isn’t just for softmax (after all, real implementations of softmax will likely already use the Taylor series!), it’s for the entire tensor-level softmax(QK) computation.

You can find papers discussing "cubic" attention, i.e. each token gets to interact with each pair of other tokens, but always in very theoretical settings with single-layer transformers on contrived synthetic tasks.

Keep in mind that LLMs have many many layers, so they have plenty of opportunity to model higher-order interactions without needing to brute force every possible combination of 10 previous tokens, of which the vast majority will be useless. Empirically, even full "quadratic" attention is not always necessary, as evidenced by the existence of linear/sparse attention variants that perform almost as well.

If you remove the terms "self", "agency", and "trivially reducible", it seems to me that a classical robot/game AI planning algorithm, which no one thinks is conscious, matches these criteria.

How do you define these terms without begging the question?

I don’t know the post you’re referring to but I highly recommend How the Immune System Works by Lauren Sompayrac. It explains the interesting parts without getting bogged down in the details of every signalling pathway, but without dumbing things down too much.

A string fixed at both ends produces harmonic sounds because of its particular structure. In order to have a non-integer overtone the ends would have to move up and down, which by construction they can't. Similarly for wind instruments: the air stops at either end and is reflected back, and a non-integer overtone would require changing the length of the tube (or sticking holes in it to allow the pressure to go to zero at the hole, effectively creating an artificial "end" of the tube).

By contrast, a freely vibrating bar (not fixed at the ends) does not have harmonic overtones. To make the bars of a xylophone, marimba, or vibraphone sound nice, you have to cut out a little "scoop" shape from the bottom of the bar to force it to vibrate such that its overtones match up with integer multiples of the fundamental frequency of the bar.

As you say, most sounds in nature do not have a harmonic spectrum, so if a fan did I would find that surprising and interesting.

It will have overtones that are integer multiples of the fundamental that give it its characteristic sound.

What I’m wondering is why would the overtones go in integer multiples (I.e. be harmonic) for a fan? A flute and a saxophone have harmonic(ish) overtones because of the physics of a vibrating column of air

Is the drone of a fan harmonic? I would’ve thought it’s more like a repetition pitch so its overtones would not be harmonic and would not exhibit a missing fundamental.

Agree with the broader point, just curious if there’s some interesting physics that creates a harmonic sound.

Apple's implementation of this is discussed here: https://news.ycombinator.com/item?id=43685714

yeah, the linked paper [1] has more detail--basically they seem to start with a seed set of "class labels" and subcategories (e.g. "restaurant review" + "steak house"). They ask an LLM to generate lots of random texts incorporating those labels. They make a differentially private histogram of embedding similarities from those texts with the private data, then use that histogram to resample the texts, which become the seeds for the next iteration, sort of like a Particle Filter.

I'm still unclear on how you create that initial set of class labels used to generate the random seed texts, and how sensitive the method is to that initial corpus.

[1] https://arxiv.org/abs/2403.01749

This approach works by randomly polling participating devices for whether they’ve seen a particular fragment, and devices respond anonymously with a noisy signal. By noisy, we mean that devices may provide the true signal of whether a fragment was seen or a randomly selected signal for an alternative fragment or no matches at all. By calibrating how often devices send randomly selected responses, we ensure that hundreds of people using the same term are needed before the word can be discoverable. As a result, Apple only sees commonly used prompts, cannot see the signal associated with any particular device, and does not recover any unique prompts. Furthermore, the signal Apple receives from the device is not associated with an IP address or any ID that could be linked to an Apple Account. This prevents Apple from being able to associate the signal to any particular device.

The way I read this, there's no discovery mechanism here, so Apple has to guess a priori which prompts will be popular. How do they know what queries to send?

I think the main advantage is that you can compute the extra parameters (the PRNG seeds) from the network weights alone, whereas most other quantization methods require simulating the quantization procedure at training time (Quantization-Aware Training) or setting them from a calibration dataset (Post-Training Quantization)

What makes this technique particular to LLM weights

This is my understanding as a non-expert.

LLM activations tend to be relatively sparse with large outliers. With linear quantization, this means you either have to clip off the outliers or you have to stretch your range to include the outliers, which wastes precious bits. Neither of these works well, so essentially all LLM quantization research is using various heuristics to get around these outliers. For example, you can do linear quantization but split the activations up into smaller blocks to make it less likely that any given block contains an outlier.

Another trick people have discovered (predates LLMs) is applying a random rotation/projection to the embeddings. This has the effect of making sure no one dimension in the vector dominates the others (which again hurts quantization). This works because in order for a single dimension to dominate, all the others have to "conspire" to be near zero. When you have 10,000+ dimensions, that's very unlikely.

This paper applies the latter trick. Instead of pre-generating the random projection matrices, they generate them on the fly on the accelerator from a seed that is fixed for each block. The seed is chosen from an offline brute-force search that needs only the weights of the network. This separates it from a lot of other quantization methods that either require calibration data or have to be simulated at training time so the network learns the quantization parameters itself.

You might think this is wasteful/might hurt performance, but it turns out that LLM inference is heavily memory-bound as it involves streaming a very large neural network into the accelerator (GPU/TPU/NPU/whatever) to operate on a relatively small amount of data, so there are lots of "free cycles" to generate these random numbers. Of course, if you care about power usage that might not be a great idea...

This doesn’t answer your question, but one thing to keep in mind is that past the very first layer, every “token” position is a weighted average of every previous position, so adjacency isn’t necessarily related to adjacent input tokens.

A borderline tautological answer might be “because the network learns that putting related things next to each other increases the usefulness of the convolutions”

Are there any technical innovations here over Moshi, which invented some of the pieces they use for their model? The only comparison I see is they split the temporal and depthwise transformers on the zeroth RVQ codebook, whereas Moshi has a special zeroth level vector quantizer distilled from a larger audio model, with the intent to preserve semantic information.

EDIT: also Moshi started with a pretrained traditional text LLM

To train DeepSeek-R1-Zero, we adopt a rule-based reward system that mainly consists of two types of rewards:

Accuracy rewards: The accuracy reward model evaluates whether the response is correct. For example, in the case of math problems with deterministic results, the model is required to provide the final answer in a specified format (e.g., within a box), enabling reliable rule-based verification of correctness. Similarly, for LeetCode problems, a compiler can be used to generate feedback based on predefined test cases.

Format rewards: In addition to the accuracy reward model, we employ a format reward model that enforces the model to put its thinking process between ‘<think>’ and ‘</think>’ tags.

This is a post-training step to align an existing pretrained LLM. The state space is the set of all possible contexts, and the action space is the set of tokens in the vocabulary. The training data is a set of math/programming questions with unambiguous and easily verifiable right and wrong answers. RL is used to tweak the model's output logits to pick tokens that are likely to lead to a correctly formatted right answer.

(Not an expert, this is my understanding from reading the paper.)

You might be interested in HippoRAG [1] which takes a graph-based approach similar to what you’re suggesting here.

[1] https://arxiv.org/abs/2405.14831

Same experience embedding random alphanumeric strings or strings of digits with smaller embedding models—very important to filter those out.

Sure, and human brains aren’t databases either, but it’s sometimes reasonable to say that we “store” and “retrieve” knowledge. All models are wrong but some are useful.

The question I’m asking is, how is this working in an LLM? How exactly do their weights encode (seemingly) the entire bible such that they can recreate long passages verbatim from a prompt that likely doesn’t appear anywhere in the training data (e.g. some vague description of a particular passage).

Has there been any serious study of exactly how LLMs store and retrieve memorized sequences? There are so many interesting basic questions here.

Does verbatim completion of a bible passage look different from generation of a novel sequence in interesting ways? How many sequences of this length do they memorize? Do the memorized ones roughly correspond to things humans would find important enough to memorize, or do LLMs memorize just as much SEO garbage as they do bible passages?

Those layers have different representation space.

Do they? Interpretability techniques like the Logit Lens [1] wouldn't work if this were the case. That author found that at least for GPT-2, the network almost immediately transforms its hidden state into a "logitable" form: you can unproject the hidden state of any layer to see how that layer incrementally refines the next token prediction.

[1] https://www.lesswrong.com/posts/AcKRB8wDpdaN6v6ru/interpreti...

On the contrary, examples like yours are the entire point of approaches like this one. If you read the HippoRAG paper cited by OP, their motivating example is almost identical to yours, and their evaluations are largely on multi-hop question answering of this kind.

The "embarrassingly simple inference technique" is to put a bunch of [MASK] tokens at the end of the prompt.

I'm having trouble understanding whether this paper is saying anything new. The original BERT paper already compared it favourably to causal models including GPT. Was there any doubt that BERT-style models could be in-context learners?

From what I gather as a non-expert, the problem with BERT is scaling/training efficiency: GPT gets C-1 training examples out of a training input of length C, but BERT only gets 0.15*C examples. Indeed, the author points out that DeBERTa required 3x more compute than GPT-3 to achieve the level of performance reported, which makes sense.

This is discussed in the "Watermarking with Synth-ID Text" section right after they define the Score function:

There are two primary factors that affect the detection performance of the scoring function. The first is the length of the text x: longer texts contain more watermarking evidence, and so we have more statistical certainty when making a decision. The second is the amount of entropy in the LLM distribution when it generates the watermarked text x. For example, if the LLM distribution is very low entropy, meaning it almost always returns the exact same response to the given prompt, then Tournament sampling cannot choose tokens that score more highly under the g functions. In short, like other generative watermarks, Tournament sampling performs better when there is more entropy in the LLM distribution, and is less effective when there is less entropy.

I don't think this is right. If you're worried about units you can calculate the (generalized) surface area to volume ratio, which turns out to be exactly D/r. In other words, as D increases, the ratio goes to infinity.

I think this fact can fairly be interpreted to mean that a high-dimensional unit sphere encloses almost no volume. The 2D cartoon drawing of a hypersphere also helps capture this: you can imagine the "spikes" stretching out and squeezing the interior portion, until it's all outside and no inside.

EDIT: another argument I've seen involves calculating the ratio of the volume of a thin shell surrounding the n-sphere's surface to its total volume. You can prove that the limit of the ratio as the dimension goes to infinity is 1. In other words, in high dimensions almost all of the volume of the sphere is concentrated near its surface.

Deborah Gordon (ant biologist) makes this argument in her book Ant Encounters. Because the ants in a colony are all sisters, the unit of reproduction is actually the colony rather than the individual ant. Great book!