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LIMDA Joint Seminar: Michael Albert

Title: First order logic of permutations. Speaker: Michael Albert, University of Otago (New Zealand).

16/11/2016 des de/d' 12:00"
Room 005, Modul C3, Campus Nord UPC
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Finite permutations can be thought of as models of the theory of two linear orders. This viewpoint sits well with the study of permutation patterns since, in that context, permutation classes are simply theories with universal axioms. However, it sits much less well with the algebraic view of permutations since we cannot recover the effect of the permutation as a function. We consider some cases where it is possible to reconcile the two views and answer questions such as: in which permutation classes is it possible to recognise the existence of fixed points (or more generally k-cycles) with a formula from the logic of two linear orders?