ИСТИНА

In this work, I present a variant of so-called ‘informational semantics’, a technique elaborated by E. Voishvillo, for two quatervalent infectious logics, Deutsch’s Sfde and Szmuc’s dSfde in order to illuminate how incompleteness and inconsistency (understood in the ‘infectious’ way) effect on the truth and falsity conditions for conjunction and disjunction. In a nutshell, I suggest two kinds of semantical conditions: ‘affirmative’ one for logics with infected gaps and ‘rejective’ one for those where gluts are infected only. With regard to the technical part, I formalize these logics in the form of natural deduction calculi, thereby solving several problems: to fill the corresponding gap in the study of a proof- theoretical aspect of infectious logics; to revise Petrukhin’s result for Sfde; to provide simple natural deduction systems for Sfde and dSfde, representing a fundamental symmetry between them and forming a convenient basis for further extensions.