Henkin semantics for reasoning with natural language


  • Michael Hahn University of Tübingen
  • Frank Richter University of Frankfurt


Henkin semantics, reasoning, reducing higher-order reasoning to first-order reasoning


The frequency of intensional and non-first-order definable operators in natural languages constitutes a challenge for automated reasoning with the kind of logical translations that are deemed adequate by formal semanticists. Whereas linguists employ expressive higher-order logics in their theories of meaning, the most successful logical reasoning strategies with natural language to date rely on sophisticated first-order theorem provers and model builders. In order to bridge the fundamental mathematical gap between linguistic theory and computational practice, we present a general translation from a higher-order logic frequently employed in the linguistics literature, two-sorted Type Theory, to first-order logic under Henkin semantics. We investigate alternative formulations of the translation, discuss their properties, and evaluate the availability of linguistically relevant inferences with standard theorem provers in a test suite of inference problems stated in English. The results of the experiment indicate that translation from higher-order logic to first-order logic under Henkin semantics is a promising strategy for automated reasoning with natural languages.

The paper is accompanied by the source code (cf. SUPP. FILES) of the grammar and reasoning architecture described in the paper.



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How to Cite

Hahn, M., & Richter, F. (2016). Henkin semantics for reasoning with natural language. Journal of Language Modelling, 3(2), 513–568. https://doi.org/10.15398/jlm.v3i2.113