Token decoder

Pinned implementation and paper LDLM @ e18c42a, not yet public · arXiv:2605.07933v1 · OpenWebText · 1024 · checkpoint, tokenizer and saved statistics not verified · How to read

in
h^\hat h [B batch, T positions, 768 d]
out
LL [B batch, T positions, 50259 vocabulary]
parameters
66,915,072
Parameters

66,915,072 parameters per instance, across its learned components

Exact per-instance accounting
ComponentCalculationParameters
Token-decoder block9,438,720×39{,}438{,}720 \times 328,316,160
Vocabulary readout768×50,259768 \times 50{,}25938,598,912
Per-instance total66,915,072

Derived from the pinned implementation’s constructors and configuration. The checkpoint’s tensors have not been counted. 306,011,162 of these parameters are trained; frozen GPT-2 and the decoder’s mask vector, 124,442,112, are not.

Explanation

There is no normalization between the last block and the readout.

The readout is a matrix of its own: it is tied neither to GPT-2’s token table nor to anything else.

Sources4

Direct evidence

The token decoder: a rotary table, the configured number of blocks, and a linear readout to the vocabulary without bias.

The implementation, pinned at revision e18c42acdfb7, not yet public

Direct evidence

The token decoder’s blocks: no softcap, no time conditioning, the gated MLP with the configured multiplier.

The implementation, pinned at revision e18c42acdfb7, not yet public

Direct evidence

The latent decoder: 12 heads of 64 features, query and key normalization, softcap 50, 6 layers, MLP multiplier 4; the token decoder has 3 blocks.

The implementation, pinned at revision e18c42acdfb7, not yet public

Direct evidence

The feature model is GPT-2, frozen; the hidden state at index −3 is extracted; the encoder and the decoder are of the Perceiver kind; the file’s vocabulary size and mask token ID are defaults that the trainer overwrites with the tokenizer’s; there are as many latents as positions, of 768 features.

The implementation, pinned at revision e18c42acdfb7, not yet public