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ZENODO
Preprint . 2026
License: CC BY
Data sources: ZENODO
ZENODO
Preprint . 2026
License: CC BY
Data sources: Datacite
ZENODO
Preprint . 2026
License: CC BY
Data sources: Datacite
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The Inefficiency of BPE Tokenizers on Symbolic Languages: An Empirical Study and a Simple Fix

descriptionPublicationkeyboard_double_arrow_right Preprint 01 Feb 2026 English Publisher:Zenodo
Authors: Cros, Adrien; Ava;

doi: 10.5281/zenodo.18770878 , 10.5281/zenodo.18770879

The Inefficiency of BPE Tokenizers on Symbolic Languages: An Empirical Study and a Simple Fix

Abstract

BPE tokenizers systematically fragment compound symbols from specialized symbolic languages into 2-5 sub-tokens, negating compression gains. We measure this on 43 pairs using the Qwen 2.5 tokenizer (151,665 tokens). Adding only 26 domain-specific tokens—a 0.017% vocabulary increase—improves mean compression by 112.4% (from 2.65x to 5.62x). Applied to a 200K-token context window, this represents a gain of 595K effective tokens. Also available in French: L'inefficience des tokenizers BPE sur les langages symboliques

Keywords

BPE tokenizer, symbolic languages, domain-specific tokenization, token compression, vocabulary extension

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selected citations
These citations are derived from selected sources.
This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Citations provided by BIP!
popularity
This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
BIP!Popularity provided by BIP!
influence
This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Influence provided by BIP!
impulse
This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
BIP!Impulse provided by BIP!
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