Abstract
Equational hybrid propositional type theory (\(\mathsf {EHPTT}\)) is a combination of propositional type theory, equational logic and hybrid modal logic. The structures used to interpret the language contain a hierarchy of propositional types, an algebra (a nonempty set with functions) and a Kripke frame. The main result in this paper is the proof of completeness of a calculus specifically defined for this logic. The completeness proof is based on the three proofs Henkin published last century: (i) Completeness in type theory, (ii) The completeness of the first-order functional calculus and (iii) Completeness in propositional type theory. More precisely, from (i) and (ii) we take the idea of building the model described by the maximal consistent set; in our case the maximal consistent set has to be named, \(\Diamond \)-saturated and extensionally algebraic-saturated due to the hybrid and equational nature of \(\mathsf {EHPTT}\). From (iii), we use the result that any element in the hierarchy has a name. The challenge was to deal with all the heterogeneous components in an integrated system.
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Acknowledgements
This research has been possible thanks to two research projects sustained by MINECO (Spain) with references FFI2013-47126-P and FFI2017-82554, respectively. We also thanks the partial support by the Portuguese Foundation for Science and Technology (FCT) through CIDMA within project UID/MAT/04106/2013 and Dalí project POCI-01-0145-FEDER-016692. Special thanks to the reviewers of this article for their valuable comments and recommendations.
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Presented by Andrzej Indrzejczak
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Manzano, M., Martins, M. & Huertas, A. Completeness in Equational Hybrid Propositional Type Theory. Stud Logica 107, 1159–1198 (2019). https://doi.org/10.1007/s11225-018-9833-5
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DOI: https://doi.org/10.1007/s11225-018-9833-5