Paraconsistent logic, existential expressibility, logical calculi.
Existential expressibility for all $k$-valued functions was proposed by A.~V. Kuz\-ne\-tsov and later was investigated in more details by S.~S.~Mar\-chen\-kov. In the present paper, we consider existential expressibility in the case of formulas defined by a logical calculus and find out some conditions for a system of formulas to be closed relative to existential expressibility. As a consequence, it has been established some pre-complete as to existential expressibility classes of formulas in some finite extensions of the paraconsistent modal logic $S5$.
Andrei Rusu
1; 3, Elena Rusu
2
1Vladimir Andrunavhievici Institute of Mathematics
and Computer Science, State University of Moldova
5, Academiei street, Chişinău, Republic of Moldova, MD2028
ORCID:
https://orcid.org/0000-0002-0259-3060
E-mail:
2Dep. of Mathematics, Technical University of Moldova
168, Stefan cel Mare bd, Chisinau, Republic of Moldova, MD-2004
ORCID:
https://orcid.org/0000-0002-2473-0353
E-mail:
3Dep. of Mathematics and Informatics, Ovidius University of Constanţa
124, Mamaia Bd., Constanţa, Romania, 900527
E–mail: andrei.rusu@365.univ-ovidius.ro