Semantic Content Determines Algorithmic Performance

Fuente: arXiv
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Hauptverfasser: Ríos-García, Martiño, Alampara, Nawaf, Jablonka, Kevin Maik
Format: Preprint
Veröffentlicht: 2026
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author Ríos-García, Martiño
Alampara, Nawaf
Jablonka, Kevin Maik
author_facet Ríos-García, Martiño
Alampara, Nawaf
Jablonka, Kevin Maik
contents Counting should not depend on what is being counted; more generally, any algorithm's behavior should be invariant to the semantic content of its arguments. We introduce WhatCounts to test this property in isolation. Unlike prior work that conflates semantic sensitivity with reasoning complexity or prompt variation, WhatCounts is atomic: count items in an unambiguous, delimited list with no duplicates, distractors, or reasoning steps for different semantic types. Frontier LLMs show over 40% accuracy variation depending solely on what is being counted - cities versus chemicals, names versus symbols. Controlled ablations rule out confounds. The gap is semantic, and it shifts unpredictably with small amounts of unrelated fine-tuning. LLMs do not implement algorithms; they approximate them, and the approximation is argument-dependent. As we show with an agentic example, this has implications beyond counting: any LLM function may carry hidden dependencies on the meaning of its inputs.
format Preprint
id arxiv_https___arxiv_org_abs_2601_21618
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Semantic Content Determines Algorithmic Performance
Ríos-García, Martiño
Alampara, Nawaf
Jablonka, Kevin Maik
Artificial Intelligence
Computation and Language
cs.LG
Counting should not depend on what is being counted; more generally, any algorithm's behavior should be invariant to the semantic content of its arguments. We introduce WhatCounts to test this property in isolation. Unlike prior work that conflates semantic sensitivity with reasoning complexity or prompt variation, WhatCounts is atomic: count items in an unambiguous, delimited list with no duplicates, distractors, or reasoning steps for different semantic types. Frontier LLMs show over 40% accuracy variation depending solely on what is being counted - cities versus chemicals, names versus symbols. Controlled ablations rule out confounds. The gap is semantic, and it shifts unpredictably with small amounts of unrelated fine-tuning. LLMs do not implement algorithms; they approximate them, and the approximation is argument-dependent. As we show with an agentic example, this has implications beyond counting: any LLM function may carry hidden dependencies on the meaning of its inputs.
title Semantic Content Determines Algorithmic Performance
topic Artificial Intelligence
Computation and Language
cs.LG
url https://arxiv.org/abs/2601.21618