Abstract

coherence theorem. In [20] R.Voreadou presented a description all non-equivalent pairs of canonical maps (non-commutative diagrams in F(A) ) in terms of two classes W 0 and W . The class W 0 was the class of "generating" pairs, in the sense, that all the pairs of W were obtained from the pairs belonging to W 0 by certain rules. According to R.Voreadou, two canonical maps are not equivalent iff they belong to W . R.Voreadou's method was 1) to prove an "abstract coherence" theorem (in our terms, that if two derivations /; ' with the same final sequent do not belong to W , then they are equivalent) and 2) to build a model (also a kind of calculus in Voreadou's case) where the pairs /; ' belonging to W are interpreted as non-commutative diagrams. Since recently the author found a mistake in R.Voreadou's proof of her "abstract coherence theorem" (there is a counterexample to the proposition 2 [20], p.3), in this work the definition of R.Voreadou's classes is modified in such a way, that ge...

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