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arXiv:2412.06769cs.CL

Training Large Language Models to Reason in a Continuous Latent Space

Shibo Hao, Sainbayar Sukhbaatar, DiJia Su, Xian Li, Zhiting Hu, Jason Weston, Yuandong Tian

Abstract

Large language models (LLMs) are typically constrained to reason in the language space, where they express the reasoning process through a chain-of-thought (CoT) to solve complex problems. However, the language space may not always be optimal for reasoning. Most word tokens primarily ensure textual coherence and are not essential for reasoning, while some critical tokens require complex planning and pose challenges to LLMs. To explore the potential of reasoning beyond language, we introduce a new paradigm called Coconut (Chain of Continuous Thought). Coconut utilizes the last hidden state of the LLM as a representation of the reasoning state, termed "continuous thought." Instead of decoding this state into words, we feed it back to the model as the next input embedding directly in the continuous space. This latent reasoning paradigm enables an advanced reasoning pattern, where continuous thoughts can encode multiple alternative next steps, allowing the model to perform a breadth-first search (BFS) rather than committing prematurely to a single deterministic path as in CoT. Coconut outperforms CoT on logical reasoning tasks that require substantial search during planning and achieves a better trade-off between accuracy and efficiency.

arXiv comments
Accepted to COLM 2025
Journal reference
DOI
Subjects
cs.CLComputation and Language

On Hacker News

Linked by 20 identifiable commenters in 21 comments across 18 threads, from Dec 2024 to Sep 2026. Found in 2 HN submissions from Dec 2024 to Apr 2026. Open submission discussions.

Comments linking this paper, per year.

Discussed in comments18 threads

    • The recurrent depth sounds a lot more like what is described in https://dnhkng.github.io/posts/rys/ - a way to add depth to a network without increasing the number of parameters. e: While the actual CoT in neuralese paper is Facebook's Coconut https://arxiv.org/abs/2412.06769…

      tveitaView on HNParent context

    • Is there a more technical source that tells what is being done? I assume it's about reasoning in latent space e.g. the coconut paper[1]? I disagree with the "experts" there, as if latent-space reasoning will only cause proper interpretability research rather than taking the CoT…

      supriyo-biswasView on HNParent context

    • "Latent" means it (the space) is there all the time but usually not exposed or apparent. Latent space is a high-dimensional space that is not legible to humans, so normally reasoning gets constrained to progress in tokens instead so that it can be evaluated. I think…

      entropeView on HNParent context

    • I saw that idea described as a step in AI 2027 (they call it "neuralese" and eyeballing the site, it's still labeled a hypothetical/future development), but AFAIK no one implemented/deployed this yet. EDIT: They link to a Meta paper from 2024/2025 though…

      TeMPOraLView on HNParent context

  1. Claude Opus 4.7 1 comment
    • > If that's true, then we're following the timeline Literally just a citation of Meta's Coconut paper[1]. Notice the 2027 folk's contribution to the prediction is that this will have been implemented by "thousands of Agent-2 automated researchers...making major algorithmic…

      magicalistView on HNParent context

    • natural language may provide part of the scaffolding for reasoning, but the capability itself seems to depend more on learned transformations over internal representations than on language alone refs: https://arxiv.org/abs/2412.17819 https://arxiv.org/abs/2412.06769

      a-t-c-gView on HNParent context

    • > extra attention head were added that queried the KV data from lower layers Isn't this sort of similar to latent looping? E.g. [1]. But actually as [2] argues, even that wasn't a good experiment because it used the very last hidden state, which is too close to the logits and…

      krackersView on HNParent context

    • Unfortunately I think the competitive pressures to improve model performance makes this kind of monitor-ability is short-lived. It's just not likely that textual reasoning in english ismost optimal. Researchers are already pushing in this direction…

      vonneumannstanView on HNParent context

    • There’s the coconut paper by meta, which kind of does a similar thing by reasoning in the latent space instead of doing it in tokens: https://arxiv.org/abs/2412.06769 Given that anthropic’s interpretability work finds that CoT does not reliably predict the model’s internal…

      supriyo-biswasView on HNParent context

    • > Just because your sampler picks a sequence of tokens that contain incorrect reasoning doesn't mean a useful reasoning trace isn’t also contained within the latent space. That's essentially the core idea in Coconut[1][2], to keep the reasoning traces in a continuous space. [1]…

      woadwarrior01View on HNParent context

  2. The Llama 4 herd 1 comment
    • > It's interesting that there are no reasoning models yet This may be merely a naming distinction, leaving the name open for a future release based on their recent research such as coconut[1]. They did RL post-training, and when fed logic problems it appears to do significant…

      voxgenView on HNParent context

    • > I suppose that raises another questions: Do LLMs "think" in language? Or do they think in a more abstract space, then translate it to language later? My money is on the latter. The processing happens in latent space and then is converted to tokens/token space. There is…

      eightysixfourView on HNParent context

    • Would be curious to know how this stacks up against Coconut [1] which also uses latent space for reasoning. [1] https://arxiv.org/abs/2412.06769

      scribuView on HNParent context

    • Paper: https://arxiv.org/abs/2412.06769 The link is in the OP, hidden away in an image caption fir some reason.

      CGamesPlayView on HNParent context

    • The official pdf for the paper is at https://arxiv.org/pdf/2412.06769 I can find "Coconut" 54 times in the PDF. The movie does not look made up.

      davidhowlettView on HNParent context

    • Explicit <eot> is only used in training. At inference time, the paper says: > A challenge lies in determining when to switch between latent and language modes. As we focus on the problem-solving setting, we insert a <bot> token immediately following the question tokens. For…

      avodonosovView on HNParent context

  3. GPT-5 is behind schedule 1 comment
    • I think the wildest thing is actually Meta’s latest paper where they show a method for LLMs reasoning not in English, but in latent space https://arxiv.org/pdf/2412.06769 I’ve done research myself adjacent to this (mapping parts of a latent space onto a manifold), but this is a…

      exhazeView on HNParent context

    • I think you mean this: https://arxiv.org/abs/2412.06769 From what I can see, presuming o3 is a progression of o1 and has good level of accountabiltiy bubbling up during 'inference' (i.e. "Thinking about ___") then I'd say it's just using up millions of old-school tokens (the 44…

      padolseyView on HNParent context

    • Large language models (LLMs) are restricted to reason in the “language space”, where they typically express the reasoning process with a chain-of-thought (CoT) to solve a complex reasoning problem. However, we argue that language space may not always be optimal for reasoning.…

      verdvermView on HNParent context

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