
Authors:
Newton C.A.da COSTA and F.A.DORIA
Title:On the existence of very difficult satisfiability problem
Pages:122133
File:bibtex
Abstract ( + )
[Abstract]

Authors:
Krister SEGERBERG
Title:How many logically constant actions are there?
Pages:134139
File:bibtex
Abstract ( + )
[Abstract]

Authors:
Gordon BEAVERS
Title:Distribution in Lukasiewicz logics
Pages:140146
File:bibtex
Abstract ( + )
[Abstract]

Authors:
Katarzyna PALASINSKA
Title:Threeelement nonfinitely axiomatizable matrices
Pages:147151
File:bibtex
Abstract ( + )
[Abstract]

Authors:
Ewa GRACZYNSKA
Title:A word problem for normal and regular equations
Pages:152155
File:bibtex
Abstract ( + )
We deal with two kinds of special equations: normal and regular. Our aim is to prove a theorem on the equivalence of the solvability of the word problem for a theory and its normal (regular) part.

Authors:
Piotr LUKOWSKI
Title:Matrixframe semantics for ISCI and INT
Pages:156162
File:bibtex
Abstract ( + )
The main aim of this paper is to present such a semantics for ISCI (intuitionistic sentential calculus with identity) which could be an intuitionistic analogue of SCImodel. The desired semantics in the form of the class of the socalled ISCImodels is in particular case a semantics for ``ordinary'' propositional intuitionism (INT). This problem will be also dealt with in this work. Notice that both semantics take on the one hand after the matrix approach of R. Suszko and after the Grzegorczyk's idea of frame on the other hand. The presentation of the valuationframe semantics for INT will be accompanied by its comparison with the class of INTmodels. Finally, we shall end the analysis setting INTmodel together with the wellknown GrzegorczykKripke's model for INT.

Authors:
R.ZUBER
Title:A note on unary rules and a complete syntactic characterisation of propositional calculi
Pages:163167
File:bibtex
Abstract ( + )
This note contains a slight generalization of a result proved by Maduch and concerning the conditions of existence of a finite set of rejected axioms permitting the generation of all nontheorems for a given propositional calculus. Maduch gave a criterion for the existence of the finite set of rejected axioms in the case when only two ``classical'' rules of rejection, i.e. the rule based on detachment and the rule based on the substitution rule, are used. In the present note I show that the same criterion applies for a large class of propositional logics where some unary rules of rejection are additionally used.

Authors:
Max Peter URCHS
Title:On determinism  still unproved in classical logic
Pages:168
File:bibtex
Abstract ( + )
[Abstract]