Vladimir Vasyukov

In 1926 D.Mourdoukhay-Boltovskoy introduced a hypersillogistic which according to him relates to the traditional syllogistic as a four-dimensional space relates to the three-dimensional space. Unfortunately, his note was too brief to understand the conception introduced. His remark from 1929 in which he refers to N. Vasiliev’s metalogic furnishes the clue to hypersyllogistic. In the paper the semantic of model schemes for hypersillogistic is proposed and some possible translations into traditional syllogistic are discussed.

The ternary, not binary, Kripke-type relation on a set of possible worlds is an essential part of the semantics of entailment by Routley-Meyer [2]. The unpopularity of such approach among many logicians is due to its intuitive vague content and complexity. An attempt is made to use not one ternary relation but two binary relations and necessity of bibinarness is demonstrated. It is shown that both semantics are equal hence the soundness and completeness of the system R of entailment can be established with the respect to the bibinary semantics. Furthermore, the ternary semantic with discrete matrix for Lukasiewicz system Lℵ0 , which was proposed in [3], could be transformed into the bibinary one and it leads to the conclusion of the completeness and soundness of Lℵ0 with the respect to the bibinary semantic. The brief consideration of the bibinary semantic intuitive content is added, which further logical study could be based on

.  How, why and what for we should combine logics is perfectly well explained in a number of works concerning this issue. But the interesting question seems to be the nature and the structure of the general universe of possible combinations of logical systems. Adopting the point of view of universal logic in the paper the categorical constructions are introduced which along with the coproducts underlying the fibring of logics describe the inner structure of the category of logical systems. It is shown that categorically the universe of universal logic turns out to be a topos and a paraconsistent complement topos.

In 1995 N. C. A. da Costa and F. Doria proposed the modaltype elegant axiomatization of Jaśkowski’s discussive logic D2. Yet his ownproblem which was formulated in 1975 in a following way: Is it possible toformulate natural and simple axiomatization for D2, employing classical disjunction and conjunction along with discussive implication and conjunctionas the only primitive connectives? — still seems left open. The matter of factis there are some axiomatizations of D2 proposed, e.g., by T. Furmanowski, J. Kotas and N. C. A. da Costa , G. Achtelik, L. Dubikajtus,E. Dudek and J. Konior , satisfying da Costa’s conditions, but they arerather looking very complicated and unnatural. An attempt is made to solveda Costa’s problem. The new axiomatization of D2 is proposed essentiallybased on da Costa’s-Doria axiomatization from 1995

In [12] it was shown that the factor semantics based on the notion ofT-F-sequences is a correct model of the ukasiewicz's infinite-valued logics. But we could not consider some important aspects of the structure of this model because of the short size of paper. In this paper we give a more complete study of this problem: A new proof of the completeness of the factor semantic for ukasiewicz's logic using Wajsberg algebras [3] (and not MV-algebras in [1]) and Symmetrical Heyting monoids [7] is proposed. Some consequences of such an approach are investigated.