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Large Concept Models: Language Modeling in a Sentence Representation Space

LCM team, Loïc Barrault, Paul-Ambroise Duquenne

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Maha Elbayad, Artyom Kozhevnikov, Belen Alastruey, Pierre Andrews, Mariano Coria, Guillaume Couairon, Marta R. Costa-jussà, David Dale, Hady Elsahar, Kevin Heffernan, João Maria Janeiro, Tuan Tran, Christophe Ropers, Eduardo Sánchez, Robin San Roman, Alexandre Mourachko, Safiyyah Saleem, Holger Schwenk

2024 · arXiv

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From the abstract

LLMs have revolutionized the field of artificial intelligence and have emerged as the de-facto tool for many tasks. The current established technology of LLMs is to process input and generate output at the token level. This is in sharp contrast to humans who operate at multiple levels of abstraction, well beyond single words, to analyze information and to generate creative content. In this paper, we present an attempt at an architecture which operates on an explicit higher-level semantic representation, which we name a concept. Concepts are language- and modality-agnostic and represent a higher level idea or action in a flow. Hence, we build a "Large Concept Model". In this study, as proof of feasibility, we assume that a concept corresponds to a sentence, and use an existing sentence embedding space, SONAR, which supports up to 200 languages in both text and speech modalities. The Large Concept Model is trained to perform autoregressive sentence prediction in an embedding space. We explore multiple approaches, namely MSE regression, variants of diffusion-based generation, and models operating in a quantized SONAR space. These explorations are performed using 1.6B parameter models and training data in the order of 1.3T tokens. We then scale one architecture to a model size of 7B parameters and training data of about 2.7T tokens. We perform an experimental evaluation on several generative tasks, namely summarization and a new task of summary expansion. Finally, we show that our model exhibits impressive zero-shot generalization performance to many languages, outperforming existing LLMs of the same size. The training code of our models is freely available.

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3 selected excerpts · 3 total mentions

aspenmartin
Neutral mention · rule
I don’t think for this approach it sounds like, this is related to the large concept model: https://arxiv.org/abs/2412.08821, where the latent space is SONAR, which is very much designed for this purpose. You learn SONAR embeddings so that every sentence with the same semantic meaning gets mapped to the same latent representation. So you can have e.g. a French SONAR encoder and a Finnish SONAR encoder, trained separately with large scale corpi of paired sentences with the same meaning (basically the same thing you would use for learning translation models directly, but for SONAR you don’t need to train a single model per pair of languages). The LCM then works in this language-agnostic SONAR space which means it does (in principle) learn concepts from texts or speech in all supported languages
naasking
Neutral mention · rule
> the behavior of LLMs is not thanks to a learned world model, but to brute force memorization of incomprehensibly abstract rules governing the behavior of symbols, i.e. a model of syntax. I think reinforcing this distinction between syntax and semantics is wrong. I think what LLMs have shown is that semantics reduces to the network of associations between syntax (symbols). So LLMs do learn a world model if trained long enough, past the "grokking" threshold, but they are learning a model of the world that we've described linguistically, and natural language is ambiguous, imprecise and not always consistent. It's a relatively anemic world model in other words. Different…
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modalities help because they provide more complete pictures of concepts we've named in language, which fleshes out relationships that may not have been fully described in natural language. But to do this well, the semantic network built by an LLM must be able to map different modalities to the same "concept". I think Meta's Large Concept Models is promising for this reason: https://arxiv.org/abs/2412.08821 This is on the path to what the article describes that humans do, ie. that many of our skills are developed due to "overlapping cognitive structures", but this is still a sort of "multimodal LLM", and so I'm not persuaded by this article's argument of needing embodiment and such. > but it is clear that there are many problems in the physical world that cannot be fully represented by a system of symbols and solved with mere symbol manipulation. That's not clear at all, and the link provided in that sentence doesn't suggest any such thing.
AlexCoventry
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Not an insider, but: I don't know about you, but I certainly don't generate text autoregressively, token by token. Also, pretty sure I don't learn by global updates based on taking the derivative of some objective function of my behavior with respect to every parameter defining my brain. So there's good biological reason to think we can go beyond the capabilities of current architectures. I think probably an example of the kind of new architectures he supports is FB's Large Concept Models [1]. It's still a self-attention, autoregressive architecture, but the unit of regression is a sentence rather than a token. It maps sentences into a latent space via an autoencoder architecture, then has a transformer architecture in which the tokens are elements in that latent space. [1] https://arxiv.org/abs/2412.08821

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