Refutation calculi for certain intermediate propositional logics.
Tomasz Skura · Notre Dame Journal of Formal Logic · 1992
Using simple algebraic methods we give Lukasiewicz-style refutation calculi for the following intermediate logics: finite logics, LC, Yankov's logic, the logic of the weak law of excluded middle, Medvedev's logic, and certain logics without the finite model property.( mp) Hα ("Ha" reads "α is refutable".)Of course r s b reverses the substitution rule, and r mp reverses the modus ponens rule.