
Authors:
Joanna GRYGIEL
Title:Some Properties of Hirreducible Lattices
Pages:7179
File:bibtex
Abstract ( + )
We describe the method of decomposing lattices via tolerance relations and introduce the notion of Hirreducibility. Then we characterize some classes of Hirreducible lattices, which appears to be useful for description of blocks of the skeleton tolerance of finite modular and distributive lattices.

Authors:
Tadeusz LITAK
Title:Some Notes of Superintuitionistic Logic of Chequered Subsets of R^{ω}
Pages:8186
File:bibtex
Abstract ( + )
We are going to investigate the superintuitionistic analogue of the modal logic of hequered subsets of R^{ω} introduced by van Benthem. It will be observed that this logic possesses disjunction property, contains Scott axiom, fails to contain KreiselPutnam axiom and is not structurally complete. We will prove that it is a sublogic of Medvedev logic ML.

Authors:
Gemma ROBLES and Jose M. MENDEZ
Title:The Logic B and the Reductio Axioms
Pages:8794
File:bibtex
Abstract ( + )
We study the possibilities of introducing the reductio axioms in Routley's basic logic B. We show how to define special reductio and conjecture that full reductio cannot be introduced. Complete relational ternary semantics are provided for all the logics in the paper.

Authors:
Zofia KOSTRZYCKA
Title:On Formulas with one Variable in some Fragment of Grzegorczyk's Modal Logic
Pages:95106
File:bibtex
Abstract ( + )
In this paper we examine normal extensions of Grzegorczyk's logic over the language {>, Box} with one propositional variable.

Authors:
Zofia KOSTRZYCKA
Title:On the Density of Truth in Grzegorczyk's Modal Logic
Pages:107120
File:bibtex
Abstract ( + )
The paper is an attempt to count the proportion of tautologies of Grzegorczyk's modal calculus among all formulas. We take recourse of some theorems proved in On Formulas with one Variable in some Fragment of Grzegorczyk's Modal Logic, Z.Kostrzycka, BSL 33/2.