On the structure of paraconsistent extensions of Johansson's logic

On the compactness property of extensions of first-order G"{o}del logic

We study three kinds of compactness in some variants of G"{o}del logic: compactness,entailment compactness, and approximate entailment compactness.For countable first-order underlying language we use the Henkinconstruction to prove the compactness property of extensions offirst-order g logic enriched by nullary connective or the Baaz'sprojection connective. In the case of uncountable first-orde...

On Paraconsistent Weakening of Intuitionistic Negation

In [1], systems of weakening of intuitionistic negation logic called Zn and CZn were developed in the spirit of da Costa’s approach(c.f. [2]) by preserving, differently from da Costa, its fundamental properties: antitonicity, inversion and additivity for distributive lattices. However, according to [3], those systems turned out to be not paraconsistent but extensions of intuitionistic logic. Ta...

Equality propositional logic and its extensions

We introduce a new formal logic, called equality propositional logic. It has two basic connectives, $boldsymbol{wedge}$ (conjunction) and $equiv$ (equivalence). Moreover, the $Rightarrow$ (implication) connective can be derived as $ARightarrow B:=(Aboldsymbol{wedge}B)equiv A$. We formulate the equality propositional logic and demonstrate that the resulting logic has reasonable properties such a...

Some Propositional paraconsistent logics C-extensions

Modal Extensions of Sub-classical Logics for Recovering Classical Logic

In this paper we introduce non-normal modal extensions of the sub-classical logics CLoN, CluN and CLaN, in the same way that S0.5 extends classical logic. The first modal system is both paraconsistent and paracomplete, while the second one is paraconsistent and the third is paracomplete. Despite being non-normal, these systems are sound and complete for a suitable Kripke semantics. We also show...