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arXiv · 1005.3731

Nominal Unification from a Higher-Order Perspective

Jordi Levy·Mateu Villaret
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Abstract

Nominal Logic is a version of first-order logic with equality, name-binding, renaming via name-swapping and freshness of names. Contrarily to higher-order logic, bindable names, called atoms, and instantiable variables are considered as distinct entities. Moreover, atoms are capturable by instantiations, breaking a fundamental principle of lambda-calculus. Despite these differences, nominal unification can be seen from a higher-order perspective. From this view, we show that nominal unification can be reduced to a particular fragment of higher-order unification problems: Higher-Order Pattern Unification. This reduction proves that nominal unification can be decided in quadratic deterministic time, using the linear algorithm for Higher-Order Pattern Unification. We also prove that the translation preserves most generality of unifiers.

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Jordi Levy, Mateu Villaret. 2010-05-20. Nominal Unification from a Higher-Order Perspective. https://doi.org/10.1145/2159531.2159532

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