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Undecidable properties of superintuitionistic logics. (Russian) Zbl 0840.03018

A property \(P\) of superintuitionistic logics (i.e., extensions of intuitionistic propositional logic Int) is decidable if there is an algorithm recognizing, given a formula \(A\), whether \(\text{Int} + A\) has \(P\) or not. The paper develops methods for proving the undecidability of properties of those logics and applies them in many particular cases. Undecidable properties of modal logics containing S4 and K4 are also discussed.

MSC:

03B55 Intermediate logics
03B45 Modal logic (including the logic of norms)
03B25 Decidability of theories and sets of sentences
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