Speaker: Mikael Cavallin (Lausanne)

Title: Branching Problems for Representations of Simple Algebraic Groups


Let \(Y\) be a simply connected simple algebraic group of classical type over an algebraically closed field \(K\) of characteristic \(p\geq 0.\) Also let \(X\) be a closed connected subgroup of \(Y\) and consider a non-trivial irreducible \(p\)-restricted rational \(KY\)-module \(V.\) In this talk, we investigate the triples \((Y,X,V)\) such that \(X\) acts with exactly two composition factors on \(V\) and see how it generalizes a question initially investigated by Dynkin in the 1950s (for \(K=\mathbb{C}\)), and then Seitz in the 1980s (for \(K\) arbitrary).