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Functorial and non-functorial sums of algebras

Prof.ssa Anna Dzamojska-Dzienio (Università Politecnica di Varsavia)

Lunedì 26 alle ore 16:30 (Aula B) e giovedì 29 alle ore 10 (Aula B) 

Abstract: The construction of a strong semilattice of groups, introduced in the semigroup theory by Clifford in 1941, was generalized further in various ways: as functorial sums (e.g., Plonka sums, Agassiz sums) and as non-functorial ones (e.g., Lallement sums), the latter being a generalization of the first ones. The aim of this talk is to recall some of these constructions and discuss connection between them. In particular, the talk will consist of two parts. The first one will have more introductory character focusing on historical remarks, examples, and applications. The second part will be more specialized and will concentrate on details of constructions and open problems.