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Language models are injective and hence invertible

arxiv.org

31–40 of 164 posts

Re: Language models are injective and hence invertible

#31
post #24

I remember hearing an argument once that said LLMs must be capable of learning abstract ideas because the size of their weight model (typically GBs) is so much smaller than the size of their training data (typically TBs or PBs). So either the models are throwing away most of the training data, they are compressing the data beyond the known limits, or they are abstracting the data into more efficient forms. That's why…

[deleted]

Re: Language models are injective and hence invertible

#32
post #24

I remember hearing an argument once that said LLMs must be capable of learning abstract ideas because the size of their weight model (typically GBs) is so much smaller than the size of their training data (typically TBs or PBs). So either the models are throwing away most of the training data, they are compressing the data beyond the known limits, or they are abstracting the data into more efficient forms. That's why…

Clarification [0] by the authors. In short: no, you can't.

[0] https://x.com/GladiaLab/status/1983812121713418606

Re: Language models are injective and hence invertible

#33

I think I'm misunderstanding the abstract, but are they trying to say that given a LLM output, they can tell me what the input is? Or given an output AND the intermediate layer weights? If it is the first option, I could use as input 1 "Only respond with 'OK'" and "Please only respond with 'OK'" which leads to 2 inputs producing the same output.

Edit: reading the paper, I'm no longer sure about my statement below. The algorithm they introduce claims to do this: "We now show how this property can be used in practice to reconstruct the exact input prompt given hidden states at some layer [emp. mine]". It's not clear to me from the paper if this layer can also be the final output layer, or if it must be a hidden layer.

They claim that they can reverse the LLM (get prompt from LLM response) by only knowing the output layer values, the intermediate layers remain hidden. So, Their claim is that indeed you shouldn't be able to do that (note that this claim applies to the numerical model outputs, not necessarily to the output a chat interface would show you, which goes through some randomization).

Re: Language models are injective and hence invertible

#34
post #27
post #24

I remember hearing an argument once that said LLMs must be capable of learning abstract ideas because the size of their weight model (typically GBs) is so much smaller than the size of their training data (typically TBs or PBs). So either the models are throwing away most of the training data, they are compressing the data beyond the known limits, or they are abstracting the data into more efficient forms. That's why…

The input isn't the training data, the input is the prompt.

Ah ok, for some reason that wasn't clear for me.

Re: Language models are injective and hence invertible

#35
post #32
post #24

I remember hearing an argument once that said LLMs must be capable of learning abstract ideas because the size of their weight model (typically GBs) is so much smaller than the size of their training data (typically TBs or PBs). So either the models are throwing away most of the training data, they are compressing the data beyond the known limits, or they are abstracting the data into more efficient forms. That's why…

Clarification [0] by the authors. In short: no, you can't. [0] https://x.com/GladiaLab/status/1983812121713418606

Thanks - seems like I'm not the only one who jumped to the wrong conclusion.

Re: Language models are injective and hence invertible

#36

Earlier quoted context omitted.

The nature of high-dimensional spaces kind of intuitively supports the argument for invertability though, no? In the sense that: > I would expect the chance of two inputs to map to the same output under these constraints to be astronomically small.

That would be purely statistic and not based on any algorithmic insight. In fact for hash functions it is quite a common problem that this exact assumption does not hold in the end, even though you might assume so for any "real" scenarios.

I'm not quite getting your point. Are you saying that their definition of "collision" is completely arbitrary (agreed), or that they didn't use enough data points to draw any conclusions because there could be some unknown algorithmic effect that could eventually cause collisions, or something else?

Re: Language models are injective and hence invertible

#37

>we confirm this result empirically through billions of collision tests on six state-of-the-art language models, and observe no collisions This sounds like a mistake. They used (among others) GPT2, which has pretty big space vectors. They also kind of arbitrarily define a collision threshold as an l2 distance smaller than 10^-6 for two vectors. Since the outputs are normalized, that corresponds to a ridiculously tiny…

As I read it, what they did there was a sanity-check by trusting the birthday paradox. Kind of: "If you get orthogonal vectors due to mere chance once, that's okay, but you try it billions of times and still get orthogonal vectors every time, mere chance seems a very unlikely explanation."

Re: Language models are injective and hence invertible

#39

Earlier quoted context omitted.

The nature of high-dimensional spaces kind of intuitively supports the argument for invertability though, no? In the sense that: > I would expect the chance of two inputs to map to the same output under these constraints to be astronomically small.

That would be purely statistic and not based on any algorithmic insight. In fact for hash functions it is quite a common problem that this exact assumption does not hold in the end, even though you might assume so for any "real" scenarios.

> That would be purely statistic and not based on any algorithmic insight.

This is machine learning research ?

Re: Language models are injective and hence invertible

#40

Actually if you prompt: Answer to this question with "ok, got it" Answer: >Ok, got it Answer to this question with exactly "ok, got it" Answer: >Ok, got it Hence is not injective

They are looking at the continuous embeddings, not at the discrete words inferred from them
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