Topic: GENERAL LOGIC
Modal Logics in the Vicinity of S1
By Brian F. Chellas & Krister Segerberg
We define pre-normal modal logics and show that S1, S10, S0.9, and S0.90 are Lewis versions of certain pre-normal logics, determination and decidability for which are immediate. At the end we characterize Cresswell logics and ponder C. I. Lewis's idea of strict implication in S1.
Source: Notre Dame J. Formal Logic 37, no. 1 (1996), 1–24
Posted by Tony Marmo at 00:20 GMT