Topologically 0-simple semigroups.
Using classical results of infinite-dimensional geometry, we show that the isometry group of the Urysohn space, endowed with its usual Polish group topology, is homeomorphic to the separable Hilbert space ℓ²(ℕ). The proof is based on a lemma about extensions of metric spaces by finite metric spaces, which we also use to investigate (answering a question of I. Goldbring) the relationship, when A,B are finite subsets of the Urysohn space, between the group of isometries fixing A pointwise, the group...
The Local Converse Problem is to determine how the family of the local gamma factors characterizes the isomorphism class of an irreducible admissible generic representation of , with a non-archimedean local field, where runs through all irreducible supercuspidal representations of and runs through positive integers. The Jacquet conjecture asserts that it is enough to take . Based on arguments in the work of Henniart and of Chen giving preliminary steps towards the Jacquet conjecture,...