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Mat. Sb., 1989 Volume 180, Number 10, Pages 1415–1427 (Mi sm1667)

This article is cited in 11 papers

Modal companions of superintuitionistic logics: syntax, semantics, and preservation theorems

M. V. Zakharyaschev


Abstract: This paper studies the class $\mathscr I$ of superintuitionistic logics and the class $\mathscr M$ of normal extensions of the modal system S4, and the syntactic and semantic connections between the two classes, given by the mapping $\rho$ (which assigns to every modal logic its superintuitionistic fragment) and by the mappings $\tau$ and $\sigma$ (which assign to every superintuitionistic logic its smallest and its greatest companion, respectively). It is shown that from classes of relational models with respect to which a logic $L\in\mathscr I$ is complete, one can construct a class of models with respect to which the logics $\tau L$ and $\sigma L$ are complete. The relationship of inference (of canonical formulas) in logics $L$, $\tau L$ and $\sigma L$ is also described. As a consequence, preservation theorems are obtained for finite approximability, for Kripke completeness and for the disjunction property at the transition from $L$ to $\tau L$, and also for decidability at the transition to $\tau L$ and $\sigma L$.
Bibliography: 21 titles.

UDC: 510.6

MSC: Primary 03B20, 03B45, 03C40; Secondary 03F55

Received: 08.12.1988


 English version:
Mathematics of the USSR-Sbornik, 1991, 68:1, 277–289

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