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Show HN: Duplicate 3 layers in a 24B LLM, logical deduction .22→.76. No training

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Re: Show HN: Duplicate 3 layers in a 24B LLM, logical deduction .22→.76. No training

#81

Earlier quoted context omitted.

Can you cite which papers you're referring to?

Are you Turing testing?

I wouldn't even call this a Turing test, in the traditional sense. This commenter claims to have recently read several papers on this topic, and I'm curious what papers those are.

If these papers don't exist, this commenter's opinions should be disregarded, irrespective of how their comment was generated.

Re: Show HN: Duplicate 3 layers in a 24B LLM, logical deduction .22→.76. No training

#83
post #53

Earlier quoted context omitted.

Empirical findings tell a very different tale: all LLM layers use vaguely compatible internal representations. And middle layers in particular can be almost interchangeable - a lot of what they seems to be "iterative refinement of the same representations". Proven by various probes and ablations, but the most obvious one is probably the good old logit lens. This is likely to be shaped by tied embeddings and skips on…

That's interesting, could you point me to some source on these findings? It seems to me that the difference between "iterative improvement" as you put it and "close to the identity" (as in the output is close to the input for most of the volume of the input space) as I put it is fairly subtle, anyway. One experiment I would like to see is what happens to the reasoning performance if rather than duplicating the select…

https://arxiv.org/abs/2505.12540 https://arxiv.org/abs/2405.07987

These, other papers, and the lottery ticket phenomenon; what it boils down to is that any neural network like system which encodes some common mapping of a phenomenon in the context of the world - not necessarily a world model, but some "real-world thing" - will tend to map to a limited number of permutations of some archetypal representation, which will resemble other mappings of the same thing.

The lottery ticket phenomenon is a bit like the birthday paradox; there will be some number of structures in a large, random initialization of neural network weights that coincide with one or more archetypal mappings of complex objects. Some sub-networks are also useful mappings to features of one or more complex objects, which makes learning hierarchical nested networks of feature mappings easier; it's also why interpretability is so damned difficult.

Re: Show HN: Duplicate 3 layers in a 24B LLM, logical deduction .22→.76. No training

#85
post #27

Assuming the benchmarks are sound (rather than capturing a fluke), the provided explanation still does not pass the smell test. As far as I can tell, there is nothing about the training process of these models that would encourage them to make the output of any layer apart from (n-1) meaningful as the input of layer n, unless perhaps these layers were initialised as identity and the training process did not get to ch…

> there is nothing about the training process of these models that would encourage them to make the output of any layer apart from (n-1) meaningful as the input of layer n

There is something that does exactly that - the residual connections. Each layer adds a delta to it, but that means they share a common space. There are papers showing the correlation across layers, of course it is not uniform across depth, but consecutive layers tend to be correlated.

Re: Show HN: Duplicate 3 layers in a 24B LLM, logical deduction .22→.76. No training

#86
post #51

Earlier quoted context omitted.

After reading both the original post and this submission, what do you think is new here?

> The weird part: different duplication patterns create different cognitive "modes" from the same weights. Double-pass boosts math. Triple-pass boosts emotional reasoning. Interleaved doubling (13,13,14,14,15,15,16) creates a pure math specialist. Same model, same VRAM, different routing. As far as I can see that's not implied by the original post. But that's beside the point: quoting the bit where the poster says "h…

This is stated in the original post as well, under "The Beginning of LLM Neuroanatomy?" section:

  > From end-position 43 to 46, we then see solid boosts in math scores (red = good, yay). But include layer 46 or beyond, and the benefits collapse again. The hypothesis: position 47 is where a different circuit begins. Including even one step of the next recipe messes up the current recipe.

  > So the ‘math organ’ has boundaries on both sides. Too few layers and you get nothing — you’ve cut into the circuit and it can’t complete its operation. Too many layers and you also get nothing — you’ve included tissue from a neighbouring circuit that doesn’t belong. Pre-training carved these structures out of the layer stack, and they only work whole. It also doesn’t translate to other tasks, as the heatmap for EQ scores doesn’t have this patch.

  > This is a much more specific claim than “middle layers do reasoning.” It’s saying the reasoning cortex is organised into functional circuits: coherent multi-layer units that perform complete cognitive operations. Each circuit is an indivisible processing unit, and the sweeps seen in the heatmap is essentially discovering the boundaries of these circuits.

Re: Show HN: Duplicate 3 layers in a 24B LLM, logical deduction .22→.76. No training

#87

Earlier quoted context omitted.

> As far as I can tell, there is nothing about the training process of these models that would encourage them to make the output of any layer apart from (n-1) meaningful as the input of layer n Right, I had the same thought. Even if the output was in the same "format", does the LLM even have any way to know which order the outputs will go in? The ordering of the nodes is part of our representation of the network, it'…

These layers are residual layers, so what a layer does is: x = x + layer(x) so it's not too surprising that they can be used recurrently

Ah! Thank you

Re: Show HN: Duplicate 3 layers in a 24B LLM, logical deduction .22→.76. No training

#88
post #70
post #49

That weird part is kind of what I was expecting. This goes to the thing that I posted on the thread a couple of days ago. https://news.ycombinator.com/item?id=47327132 What you need is a mechanism to pick the right looping pattern, Then it really does seem to be Mixture of experts on a different level. Break the model into input path, thinking, output path. and make the thinking phase a single looping layer of many e…

If you're adding a model to do the "routing" you're basically putting learned backward connections and you end up with a RNN

Mixture of Experts already have routing models,

I'm just suggesting eliminate (or weaken) the distinction between layers and expert and have just the one, then iterate that one until its 'gpod enough' score plus (iterationcount*spontaneity) is greater than some threshold.

Re: Show HN: Duplicate 3 layers in a 24B LLM, logical deduction .22→.76. No training

#90
post #27

Assuming the benchmarks are sound (rather than capturing a fluke), the provided explanation still does not pass the smell test. As far as I can tell, there is nothing about the training process of these models that would encourage them to make the output of any layer apart from (n-1) meaningful as the input of layer n, unless perhaps these layers were initialised as identity and the training process did not get to ch…

> something happened to the model in training (RLHF?) that forcefully degraded its reasoning performance I've been seeing more people speculating like this and I don't understand why. What evidence do we have for RLHF degrading performance on a key metric like reasoning? Why would this be tolerated by model developers? Can someone point to an example of an AI researcher saying "oops, RLHF forcefully degrades reasonin…

The most obvious way would simply be excessive agreeableness. Users rate responses more highly if they affirm the user's thinking, but a general tendency to affirm would presumably result in the model being more inclined to affirm its own mistakes in a reasoning chain.

There was some research about it early on that was shared widely and shaped the folklore perception around it, such as the graph in https://static.wixstatic.com/media/be436c_84a7dceb0d834a37b3... from the GPT-4 whitepaper which shows that RLHF destroyed its calibration (ability to accurately estimate the likelihood that its guesses are correct). Of course the field may have moved on in the 2+ years that have passed since then.

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