Attention Is Not What You Need (2025)
Posted by westurner 3 days ago
Comments
Comment by mapontosevenths 3 days ago
(zt,zt+Delta) where Delta is a positive offset.
This means the model is using the next token to predict the next token. It should have been (zt,zt-Delta), or it's cheating.
I don't know if that's just the paper, or if the code was also b0rk3d.
Comment by magicalhippo 3 days ago
For each position t and offset Δ∈ such that t+Δ≤L, we form a pair (z_t,z_t+Δ).
For a given t, this produces up to m pairs:
(z_t,z_t+Δ_1),(z_t,z_t+Δ_2),….
We treat these as local neighborhoods at multiple scales. Note that the pairing is causal: we only pair t with positions strictly to its right (future), consistent with left-to-right language modeling.
So z_t is a token in the input, and z_t+Δ is some later token. Guess they could have flipped that around to (z_t-Δ, z_t) with t+Δ>=0.
Comment by mapontosevenths 3 days ago
I think you get what I'm saying, but when they compute the gate they do:
h_t_new = alpha_t * h_t + (1 - alpha_t) * g_t
If I'm reading it right g_t = geometric_mix(z_t, z_(t+delta))Which would mean that g_t includes t+Δ, which is a future token. It's leaking future tokens into the current math.
So it could just be a sign error and still be right in the code, or I could just be getting it wrong.
If I'm not though, and given that they got worse results than a standard transformer I really hope it's fixed in the code. If they do worse even when knowing the future it's bad news for the idea.
Comment by magicalhippo 3 days ago
I found this[1] repo which tries to reproduce it, and its accompanying blog post[2] uses (z_t, z_t - delta), without further mention.
Another repo[3] trying to reproduce it also does the reverse from what I can see, so (current, past).
Interestingly the first repo got underwhelming results, while the second repo matched the paper roughly. Not sure if it's related to the Claude-usage or not in the first, though it notes a lot of details were left out of the paper which is true.
[1]: https://github.com/Infatoshi/grassmann-flows/
[2]: https://github.com/Infatoshi/grassmann-flows/blob/main/blog....
Comment by mapontosevenths 2 days ago
I still don't think it will work, but I'm also fairly confident that nobody has actually reproduced it well enough to know that for sure.
Comment by imtringued 3 days ago
Not sure what the point of the paper's title is if the resulting model does not match the transformer.
Comment by magicalhippo 3 days ago
In summary, our results suggest that what we fundamentally need for strong sequence modeling is not attention as such, but a principled way for representations to move on the manifolds they inhabit. Grassmann flows provide one concrete instantiation of this idea, and we hope they will encourage further exploration of geometric alternatives to attention in the design of neural architectures.
They also note they kept the proposed model very simple to make it easier to understand (and presumably train):
In this paper we deliberately restricted ourselves to a minimal design—k = 2, no explicit global invariants—to keep the core idea clear. But we view “global invariants + local Grassmann flow” as a promising direction for future work on geometry-aware reasoning.
Comment by imtringued 3 days ago
I mean if you look at e.g Mamba 3 [0] (see page 12 and 14 for benchmarks), the perplexity is roughly the same and the benchmark scores are roughly the same. If you tell me attention doesn't matter you have to convince me by showing that you can get the same performance with a variety of architectures. In short, I would have expected the paper to be a survey across model architectures that all perform roughly the same, which then would give us the impression "hey, they're all performing the same, maybe we don't need attention after all!", instead we get to be shown that their pet architecture is worse, which is the opposite of what the headline conveys.
If I gave a random ML researcher this paper, they would just walk away and work on the next transformer-mamba hybrid.
Comment by charcircuit 3 days ago
That's why you see other attention free large language models work. But in a world with constraints on time and compute the architecture does matter because scaling does have a cost (which is dropping)
Comment by dannyw 3 days ago
Compute, data, and parameter count are the three logarithmic values that correspond to model performance.
So if you find ways of improving training efficiency (the simplest conceptually is probably local/global sliding window attention like Gemma; the latest DeepSeek and Kimis have quite fancy ones), you will be able to have more effective compute, and train smarter models while keeping data and param count the same.
If you find this fascinating and want to dive more, I encourage checking out nanochat (solid GPT-2 repro; minimal LoC); and trying to make architectural tweaks with a coding agent.
“Learning through experimentation” has never been easier or more fun in my opinion. If you have a GPU, even an older 8GB card (or a few bucks for Runpod), you can pretrain your own small language model and start experimenting / tweaking it.
Comment by addag 3 days ago
I don't get how changing the attention head (i.e sliding window attention instead of vanilla transformer) is only seen as a "compute" improvement. Indeed, it improves the complexity from quadratic to linear, but there was a reason why people used transformer and not sliding windows for so long (they were already there in 2021).
Making sliding window attention work with performances on par with vanilla transformers is a non trivial problem and is not solved by only putting more compute. This still requires "smart" ideas in that direction.
Comment by janalsncm 3 days ago
Comment by hujun236 3 days ago
Comment by api 3 days ago
The neocortex would be akin to something like a 100T neural network, and that’s with the maybe overly reductionist assumption that only synapses are doing anything when there’s a lot of biology happening in there. Every cell is filled with its own computation and state. It could be closer to a 10E model if all that is in play.
The neocortex is nowhere near the whole brain.
Architecturally the brain could be described as a slow but ultra-wide machine with colocated memory and thus an effectively enormous memory bandwidth. That lets it evaluate its whole parameter set continuously.
I keep thinking the brain must be algorithmically doing something super clever but maybe not. Maybe old mother nature just found the “bitter lesson.” Maybe it’s algorithmically inefficient and messy but there’s just a whole lot of it.
Comment by ngruhn 3 days ago
Comment by api 2 days ago
A more far-out explanation is that some form of stochastic quantum computing is going on, which has been proposed at many levels by biologists. There's some work being done on this idea. It would not be the discrete qubit form we are trying to do, which is impossible in a noisy wet environment, but something analog and stochastic.
Both are possible.
Also note that our current chips, in spite of the tiny feature sizes and a ton of optimization work, are not even close to the lower limit for energy cost of computation. They still are not very efficient.
Comment by captainbland 3 days ago
My thought is you could probably set up something similar with today's technological capabilities but it would probably take decades to train and be expensive to develop which is commercially unacceptable.
Comment by K0balt 3 days ago
Comment by peterfirefly 2 days ago
I'm afraid we don't know much more than that yet.
We have created frankenrodents with human astrocytes and they are a lot smarter than their unfranked counterparts. I bet we could learn a lot if we repeated the experiment with astrocytes from humans with different, known IQs.
Comment by famouswaffles 2 days ago
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Comment by amelius 3 days ago
(?) We actually don't know that but it is very likely.
Comment by HexPhantom 3 days ago
Comment by seamossfet 2 days ago
I don't think Grassmannian manifolds are necessarily a better representation than simple query/key inner products. It's a valid solution, and it does have advantages in some cases.
The Grassmannian is only preserving the subspace orientation, so we lose information about the actual linear map and basically throw out its basis.
Like everything, this is a trade off. You're trading information for a lower rank representation.
I'm still reading through the paper on the implementation side, but the other caveat I'd be wary of is compute. Does this projection add MACs to the overall model which would make inference slightly slower even with lower rank representations? I don't know. Like with any technique that trades constrained information representation for space/compute you _are_ widening your search space during training. I'd be curious what the impact of this is on relative data needed to train a model using this architecture versus "regular" attention.
Comment by oofbey 3 days ago
Arguably the most important aspect of transformers is that it allowed easy training of arbitrarily large models.
Comment by HexPhantom 3 days ago
Comment by oofbey 2 days ago
Efficient alternatives have been coming out for 10 years now. Flash attention is the only one that has really moved the needle - because it’s not an algorithmic compromise. It’s just a smarter way to put the parentheses around the linear algebra operations.
Comment by xpxeqy 2 days ago
Tis why Haskell, etc, will not be used to write a meaningful OS wielded at scale. Graphics mutations don't want to wait for long dead Mr Euler or whoever to be satisfied.
Having to cache states as rigorous axiomatic rules are satisfied without C like ability to cut the queue and mutate some value just moves the problems C creates being able to do that, doesn't eliminate them; thermodynamics is a bitch like that.
Math is not physics. Physics is not math. Math is merely a syntax for notation of physics like how English is a notation for allegory and metaphor.
Physics is immutable and will not break because we decide some syntax suggests it will.
Comment by gnabgib 3 days ago
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Comment by Marcuss2 2 days ago
You are likely to find kernels for Gated Delta Net 2 as Nvidia had a paper on that.
Comment by ActorNightly 2 days ago
https://news.ycombinator.com/threads?id=ActorNightly&next=49...
TLDR its not so much about the transformer, as much as expanding dimentionality. You can chose any which way to do so.
Comment by themagyar 3 days ago
Comment by neuroelectron 2 days ago
human intuition is supported by embodied experience, perception, and years of interacting with the physical and social world. An AI model's learned pattern recognition is analogous in some respects, but it isn't the same process.
intelligence may depend less on continuously scrutinizing everything than on having a good internal model, recognizing when that model is likely to fail, and knowing where to investigate.
Comment by mnaimd 2 days ago
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Comment by kooi 3 days ago
;)
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Comment by harry8 3 days ago
It should be unsurprising if comments here, made in public, capable of being challenged are far higher quality than official "peer review" which has really become a bit of a joke. Has been for quite a long time, to be fair. (And unsurprising if not, it's a web forum).
Peer reviewed and published means precisely excrement in a world where papers are not retracted and failures to replicate are refused publication by the "prestigious" "peer-reviewed" journals that published the original.
Intelligent, reasoned, knowledgeable review going back and forth with the author in public makes "peer review" seem just as silly as it usually is. Review by peer professor's indentured servants aka PhD students is often actually higher quality, if wildly dishonest and quite frankly disgraceful.
We now live in a world where LLMs can produce papers. Actual research is a little more interesting, with or without LLM. The journal peer review system doesn't seem to be helping.
Comment by hasley 3 days ago
For AI, the borders seem to have blurred a bit between academic scientists (e.g. at universities) and external scientists at companies or even private people). The problem with the latter is that it is much harder to enforce good scientific practice. Think only about the time it takes to write the state of the art of an ordinary conference paper.
I am also a bit drawn between giving everyone the chance to contribute to research and ensuring good scientific practice. Just writing down your latest ideas and successes is not the same as writing a scientific paper that shows the research in the context of past research and needs, for instance, to be much more mathematically rigorous.
Comment by harry8 2 days ago
This is nothing like academic journal peer review, where you can't see the failed submissions for the paper and why. You have no clue if the reviewers were interested in the topic, diligent, drunk or playing politics "support papers from these institutions because they're the good guys, undermine those because they are or aren't from Europe." You have no idea if the paper has since failed to replicate on multiple occasions. You have no idea if you are the first person to actually read the paper and when you have you thoughts, no matter how insightful, well articulated and supported by evidence, those thoughts do not matter to the publication process of that paper, which has been peer reviewed.
Public review by the knowledgeable who care is a very different thing to so called "peer review."
Comment by elendilm 3 days ago
It's fairly basic. For a work published on a public platform, the same guys paid by the journal can also review it if they so choose to in addition to those people in the public who were not paid by anyone.
Comment by mkremins 2 days ago
Comment by elendilm 2 days ago
The logic stands. A reviewer, even those who get zero compensation, can always review publicly published papers just like others.
Comment by blagie 3 days ago
In my academic career, I had one instance of reviewers actually reading a paper. Otherwise -- accept or reject -- the comments made clear the paper had never been actually read.
Retractions are non-existent, even with clearly proven academic malpractice.
Comment by hasley 3 days ago
Usually I got quite critical comments (positive and/or negative). Yes, sometimes a reviewer does not write even a single sentence before giving an average score to complete the review process. But this has not been the regular case.
And as a reviewer for a conference paper of 4 to 6 pages, I usually assigned 1 to 3 hours to read it (journal papers: 1 to 2 days) and to give comments.
Comment by blagie 2 days ago
Most of the rest of my papers were in completely different disciplines.
It was an awesome paper -- in my mind, groundbreaking -- but I'm not convinced anyone beyond the reviewers ever read it. I see about a dozen citations which popped up years later, clicked through a few, and they were inane.
Problem is it was work in a very, very classical field, alongside Butterworth, Chebyshev, and similar, and while quite fundamental, and with many applications, there is no contemporary research there.
My most popular papers were mostly rather.... random.
Comment by Grimblewald 2 days ago
Retractions do happen as well, especially if it's clearly proven malpractice. I've been behind 2 retractions so far, but it has never (in my experience) happened at the "contact corresponding author and seek clarification" stage of escalation. Typically it requires escalation to the journal itself.
Comment by HexPhantom 3 days ago
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Comment by elendilm 3 days ago
It's his/her prerogative to keep an online footprint or not.
Comment by erickgabriel 3 days ago
Comment by Grimblewald 3 days ago
Also, more effort into completeness needs to go in. Perhaps it is in there, but you just report an "accuracy" without defining what that means. The more I look, the more it starts becoming apparent this likely hasn't received any real human over-sight at all. "What does Grassmann mixing actually buy us?" It buys nothing, because it is a concept, Claude.
Neat idea, but in my opinion devoid of critical thinking / analysis or the level of rigour required to be suitable for broader dissemination. I'd put effort into making this a more credible body of work ASAP. Slop like this WILL cripple your standing in the field.
Comment by porkshoe 3 days ago
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Comment by helpyou840 3 days ago
Agreed.
I say: “if you want a human response, then give human effort”