We define a shallow embedding of logical proof-irrelevant Pure Type Systems (piPTSs) into minimal first-order logic. In logical piPTSs a distinguished sort *^p of propositions is assumed. Given a context Gamma and a Gamma-proposition tau, i.e., a term tau such that Gamma |- tau : *^p, the embedding translates tau and Gamma into a first-order formula F_Gamma(tau) and a set of first-order axioms Delta_Gamma. The embedding is not complete in general, but it is strong enough to correctly translate most of piPTS propositions (by completeness we mean that if Gamma |- M : tau is derivable in the piPTS then F_Gamma(tau) is provable in minimal first-order logic from the axioms Delta_Gamma). We show the embedding to be sound, i.e., if F_Gamma(tau) is provable in minimal first-order logic from the axioms Delta_Gamma, then Gamma |- M : tau is derivable in the original system for some term M. The interest in the proposed embedding stems from the fact that it forms a basis of the translations used in the recently developed CoqHammer automation tool for dependent type theory.
@InProceedings{czajka:LIPIcs.TYPES.2016.9, author = {Czajka, Lukasz}, title = {{A Shallow Embedding of Pure Type Systems into First-Order Logic}}, booktitle = {22nd International Conference on Types for Proofs and Programs (TYPES 2016)}, pages = {9:1--9:39}, series = {Leibniz International Proceedings in Informatics (LIPIcs)}, ISBN = {978-3-95977-065-1}, ISSN = {1868-8969}, year = {2018}, volume = {97}, editor = {Ghilezan, Silvia and Geuvers, Herman and Ivetic, Jelena}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.TYPES.2016.9}, URN = {urn:nbn:de:0030-drops-98533}, doi = {10.4230/LIPIcs.TYPES.2016.9}, annote = {Keywords: pure type systems, first-order logic, hammers, proof automation, dependent type theory} }
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