The next Infinite Groups Seminar will be on Monday 6 June at the University of Sydney and over the Access Grid. The speakers will be James East at 12 noon and Pallavi Dani at 2.30pm. -------------------------------------------------------------------------- 12:00, Access Grid Room, Carslaw 829 Speaker: James East (University of Western Sydney) Title: Idempotent generators in partition monoids Abstract: Partition monoids and algebras arise in representation theory in the context of Schur-Weyl duality in symmetric groups. They are also interesting from a semigroup theoretic point of view as they contain the full transformation semigroups as well as the symmetric (and dual symmetric) inverse monoids. We characterise the elements of the partition monoid which are products of idempotent partitions. The finite and infinite cases require separate treatment. Our results are similar in character to those obtained by Howie in his 1966 paper on full transformation semigroups; in fact, Howie’s results may also be deduced from ours. This is joint work with Des FitzGerald. 14:30pm, Access Grid Room, Carslaw 829 Speaker: Pallavi Dani (Louisiana State University) Title: Higher Dehn functions of Bestvina-Brady groups Abstract: The k-dimensional Dehn function of a group captures the difficulty of filling k-spheres by (k+1)-balls in a complex that models the group. I will talk about a method for modifying fillings of spheres in the complex associated with a right-angled Artin group. This can be used to obtain sharp bounds on the higher Dehn functions of certain subgroups called Bestvina-Brady groups. Similar ideas lead to estimates on higher divergence functions in right-angled Artin groups. This is joint work with Aaron Abrams, Noel Brady, Moon Duchin, and Robert Young. -------------------------------------------------------------------------