Prucnal proved, see [8] and [9], that Medvedev's logic ML of finite problems is structurally complete. So far, ML is the only known structurally complete intermediate logic with the disjunction property. Another proof of Prucnal's theorem was given by D. Skvortsov [10]. We refresh Prucnal's original argument and prove that all structurally complete intermediate logics with the disjunction property coincide on monadic formulas. The logic are also provided with appropriate Kripke frames.
2
Dostęp do pełnego tekstu na zewnętrznej witrynie WWW
We prove that the purely equivalential fragment of intuitionic logic is not axiomatizable by a finite number of axiom schemata and the modus ponens rule for equivalence as the only rule of inference.
3
Dostęp do pełnego tekstu na zewnętrznej witrynie WWW
The sum operation, as introduced by Andrzej Wroński, is used to decompose any finite distributive lattice into its Boolean fragments. The decomposition is not unique but its maximal components are uniquely determined. We define an ordering relation between these maximal Boolean fragments of a given lattice and use this link ordering to describe the structure of the lattice.
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.