ResearchResearch paperLarge Language Models1 source · Oct 6, 2026

Language Unalignability: Why Some Concepts Resist Cross-Cultural Benchmark Evaluation

Current evaluation of multilingual Large Language Models (LLMs) rests on an implicit Translation-Isomorphism Assumption (TIA): that semantic structures across languages are congruent and mutually mappable without loss of information.

Key points

  • We formalize this failure using a usage-cloud framework, representing concepts as point sets of contextualized embeddings.
  • We define $α$-unalignability as the impossibility of any mapping that simultaneously preserves lexical faithfulness (centroid correspondence) and structural faithfulness (local neighborhood topology).
  • Behaviorally, we show that FLORES-200 translation failures are predicted by language family and resource class but not by script, and that LOBSTER reasoning scores vary by family.
  • Mechanistically, we report a Representation-Intervention Gap (RIG) in a nine-model case study on Yami: the models' activations encode a regularity along which Yami groups with other low-resource and Austronesian languages, yet interventions on language-specific neurons show no demonstrated advantage over random masks: the regularity is visible but not usable by this intervention.

Sources (1)

  • [1]Language Unalignability: Why Some Concepts Resist Cross-Cultural Benchmark Evaluation
    arXiv (AI, ML, NLP, CV, robotics, multi-agent) · Oct 6, 01:10 PM
    Current evaluation of multilingual Large Language Models (LLMs) rests on an implicit Translation-Isomorphism Assumption (TIA): that semantic structures across languages are congruent and mutually mappable without loss of information.
    We formalize this failure using a usage-cloud framework, representing concepts as point sets of contextualized embeddings.

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