Abstract
Computational complexity of the semigroup fragment (of the algebraic semantics) and the implicational fragment of some fuzzy logics is studied, from the perspective of the complexity of the full logic. The available results appear to confirm the key role of the implicational fragments. Some other language fragments, as well as the notion of language fragment itself, are discussed.
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An extension is understood to be an axiomatic extension in the same language.
It follows from that paper that the implicational fragment of product logic is contained in the implicational fragment of Łukasiewicz logic; this also follows from the fact that the standard MV-algebra is isomorphic to the cut product algebra (cf. Hájek 1998).
A propositional logic can itself be regarded as a syntactic fragment of its (putative) predicate expansions.
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Acknowledgments
The author was supported by the Czech Science Foundation under the Grant Number P202/11/1632, and by the long-term strategic development financing of the Institute of Computer Science RVO:67985807.
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Communicated by A. Di Nola, D. Mundici, C. Toffalori, A. Ursini.
Dedicated to Franco Montagna, with gratitude for his contributions to logic, his support of fellow logicians, and his seasoning of serious situations with a gentle touch of humor.
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Haniková, Z. Complexity of some language fragments of fuzzy logics. Soft Comput 21, 69–77 (2017). https://doi.org/10.1007/s00500-016-2346-0
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DOI: https://doi.org/10.1007/s00500-016-2346-0