Janusz Czelakowski

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According to Frege's principle the denotation of a sentence coincides with its truth-value. The principle is investigated within the context of abstract algebraic logic, and it is shown that taken together with the deduction theorem it characterizes intuitionistic logic in a certain strong sense. A 2nd-order matrix is an algebra together with an algebraic(More)
A deductive system S (in the sense of Tarski) is Fregean if the relation of interderivability, relative to any given theory T , i.e., the binary relation between formulas f h; i : T; `S and T; `S g; is a congruence relation on the formula algebra. The multiterm deduction-detachment theorem is a natural generalization of the deductive theorem of the(More)
The aim el the article is to outline the historical background and the present state of the methodology of deductive systems invented by Alfred Tarski in the thirties. Key notions of Tax'ski's methodology are presented and discussed through the recent development of the original concepts ~nd ideas. w 1. Consequence operations Philosophical intuit ions which(More)
A b s t r a c t. A short history of equivalential logics is sketched commencing with the pioneering work of Prucnal and Wro´nski [1974]. The notion of equivalential logic is due to Tadeusz Prucnal and Andrzej Wro´nski. The short note " An algebraic characterization of the notion of structural completeness " appeared in 1974 in Bulletin of the Section of(More)