Notre Dame Journal of Formal Logic
- Notre Dame J. Formal Logic
- Volume 38, Number 2 (1997), 295-313.
Propositional Quantification in the Topological Semantics for S4
Fine and Kripke extended S5, S4, S4.2 and such to produce propositionally quantified systems , , : given a Kripke frame, the quantifiers range over all the sets of possible worlds. is decidable and, as Fine and Kripke showed, many of the other systems are recursively isomorphic to second-order logic. In the present paper I consider the propositionally quantified system that arises from the topological semantics for S4, rather than from the Kripke semantics. The topological system, which I dub , is strictly weaker than its Kripkean counterpart. I prove here that second-order arithmetic can be recursively embedded in . In the course of the investigation, I also sketch a proof of Fine's and Kripke's results that the Kripkean system is recursively isomorphic to second-order logic.
Notre Dame J. Formal Logic Volume 38, Number 2 (1997), 295-313.
First available in Project Euclid: 12 December 2002
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Kremer, Philip. Propositional Quantification in the Topological Semantics for S4 . Notre Dame J. Formal Logic 38 (1997), no. 2, 295--313. doi:10.1305/ndjfl/1039724892. http://projecteuclid.org/euclid.ndjfl/1039724892.