Monoid extensions and the Grothendieck construction

Description:  It is well known to category theorists that the Schreier theory of group extensions can be understood in terms of the Grothendieck construction on indexed categories, but the case of monoid extensions is seldom mentioned. In this talk I will describe how the classification of Schreier and weakly Schreier extensions of monoids can be obtained from generalisations of the Grothendieck construction (given by special cases of Bénabou's construction of displayed categories). I will try to explain the necessary background and to provide a description of Bénabou's construction. Date:  2021-10-28 Start Time:   16:00 Speaker:  Graham Manuell (CMUC) Institution:  CMUC, Univ. Coimbra Place:  Sala Pedro Nunes See more:   <Main>   <Informal Seminar on Categories>