ELLM: the right name for a language model that predicts in latent space and decides by energy
Energy-based latent predictive language model. Each part of the name, the project piece that realises it, the number that supports it — and what the name does not yet guarantee.
Landed here from LinkedIn? This is chapter 17 of the experiment Antivision · Latent Rehearsal. It reads on its own; if you want the beginning, it is chapter 00.
I called my model an LLM for months. The name was wrong — and not because of its size. The L in LLM stands for large, and what an LLM does is choose the next token by the probability of a forward pass. My model has 7.4 million parameters and does something else before writing: it imagines, in latent space, where each candidate would take the text, and chooses the lowest energy. The right name for that is ELLM: energy-based latent predictive language model. Every part of the name has a measured number. And one of them has a limit that is also measured: at the default setting, the lowest-energy token is the most likely token itself in 90.6% of positions.
The three points
- The first L in LLM stands for large, and describes scale. An ELLM is defined by something else: it predicts the next state in latent space for each candidate and chooses the lowest energy. The token head is still there, writing the text.
- Every part of the name has a measurement: the energy rudder takes affinity from 0.256 to 0.355 with lower perplexity; the world model, with enough data and three seeds, costs the generator about 1%, within the noise; in the regularized model, the energy of an arbitrary point in space is about four times more expensive than in the shortcut.
- The limit is measured too: at the default guardrail weight, the lowest-energy token is the most likely one in 90.6% of positions. An ELLM can decide by energy; how much it does depends on the configuration.
From the chapter, the beginning
Energy-based latent predictive language model. The right name for what Antivision builds: a language model that predicts in latent space and decides by energy. This chapter explains each word of the name, shows what has already been measured for each one, and what the name does not promise.
Until now this collection has called the system a "language model", and at times compared it with "an LLM". Both miss what it does differently.
The first L in LLM stands for large: the name describes scale. And what an LLM does, by construction, is choose the next token by the probability a forward pass assigns to each candidate. The model in this collection is not large — mini has 7.4 million parameters — and what sets it apart is not size but where it predicts and how it decides.
An ELLM — Energy-based Latent predictive Language Model — is a language model that, before emitting a token, predicts in latent space where each candidate would take the state, and chooses by minimizing an energy over those predicted futures. The token head is still there: it is what turns the state into text.
What the chapter covers · 5 sections · 6 min
- Why a name of its own
- The four parts of the name
- LLM and ELLM side by side
- What is already measured
- What the name does not promise
All chapters of the experiment · Antivision · Latent Rehearsal
- 00 · Antivision: an ELLM, a language model that rehearses in latent space before speaking
- 01 · The custom tokenizer: why 16 thousand tokens suit this corpus better than 50 thousand, and what the whole table shows
- 02 · Two architectures, one file: the fair duel between 2019 and what came after
- 03 · The geometry of the embedding: training starts with a perfect space and ruins it
- 04 · The lineage of collapse: five answers from computer vision, each measured on text
- 05 · The rudder and the world model: three versions of the same question, each measured against the last
- 06 · Method and mistakes: the rules of a legitimate comparison and the catalogue of our own errors
- 07 · Scale and budget: what it costs to reach GPT-3, and why VRAM is almost never the limit
- 08 · The workbench: serve, x-ray and train from the browser
- 09 · The hierarchical architecture: the whole project aligned to the four patterns of the world model
- 10 · What JEPA is, according to LeCun: two talks read concept by concept, and where each one applies
- 11 · Memory and horizon: two claims from LeCun that became experiments, and both hold for text
- 12 · Learned costs and inference modes: the three searches and the two sources of energy, measured
- 13 · The corrections from LeCun's talks: failure, passage, flag, measurement
- 14 · Consulted memory: a bank of abstract states read by attention
- 15 · What it costs and what it delivers: us, GPT-1 and GPT-2 on the only ruler valid across tokenizers
- 16 · The minimum was off the list: the day I measured my own search by energy
- 17 · ELLM: the right name for a language model that predicts in latent space and decides by energy
- 18 · Searching better does not fix the energy: three searches, the same text
- 19 · The inversion that did not repeat: the world model's cost appears once the ruler stops swinging
- 20 · What changed on 17/09: two new chapters and two corrections

Writes the GPT-2 course and runs the Antivision experiment, measuring every run before publishing the number. The LinkedIn posts start here and end in the chapters.
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