LZ Penalty: An information-theoretic repetition penalty for autoregressive language models

Fuente: arXiv
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Hauptverfasser: Ginart, Antonio A., Kodali, Naveen, Lee, Jason, Xiong, Caiming, Savarese, Silvio, Emmons, John R.
Format: Preprint
Veröffentlicht: 2025
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author Ginart, Antonio A.
Kodali, Naveen
Lee, Jason
Xiong, Caiming
Savarese, Silvio
Emmons, John R.
author_facet Ginart, Antonio A.
Kodali, Naveen
Lee, Jason
Xiong, Caiming
Savarese, Silvio
Emmons, John R.
contents We introduce the LZ penalty, a penalty specialized for reducing degenerate repetitions in autoregressive language models without loss of capability. The penalty is based on the codelengths in the LZ77 universal lossless compression algorithm. Through the lens of the prediction-compression duality, decoding the LZ penalty has the interpretation of sampling from the residual distribution after removing the information that is highly compressible. We demonstrate the LZ penalty enables state-of-the-art open-source reasoning models to operate with greedy (temperature zero) decoding without loss of capability and without instances of degenerate repetition. Both the industry-standard frequency penalty and repetition penalty are ineffective, incurring degenerate repetition rates of up to 4%.
format Preprint
id arxiv_https___arxiv_org_abs_2504_20131
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle LZ Penalty: An information-theoretic repetition penalty for autoregressive language models
Ginart, Antonio A.
Kodali, Naveen
Lee, Jason
Xiong, Caiming
Savarese, Silvio
Emmons, John R.
Machine Learning
Artificial Intelligence
Information Theory
We introduce the LZ penalty, a penalty specialized for reducing degenerate repetitions in autoregressive language models without loss of capability. The penalty is based on the codelengths in the LZ77 universal lossless compression algorithm. Through the lens of the prediction-compression duality, decoding the LZ penalty has the interpretation of sampling from the residual distribution after removing the information that is highly compressible. We demonstrate the LZ penalty enables state-of-the-art open-source reasoning models to operate with greedy (temperature zero) decoding without loss of capability and without instances of degenerate repetition. Both the industry-standard frequency penalty and repetition penalty are ineffective, incurring degenerate repetition rates of up to 4%.
title LZ Penalty: An information-theoretic repetition penalty for autoregressive language models
topic Machine Learning
Artificial Intelligence
Information Theory
url https://arxiv.org/abs/2504.20131