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)