Extensions of Weyl and Schur functors (Q833997)

The article concentrates on work within the category of strict polynomial functors over a fixed field of finite characteristic (examples are \(d\)-fold tensor, exterior, symmetric and divided power functors\({\dots)}\); this is a third part in the author's related series of papers with the goal of computing Ext-groups between simple objects in this category. The author studies the Ext-groups in this category. One of the main results is a computation of the Ext-groups between twisted Weyl and Schur functors for a large class of Young diagrams. One of the results in the paper generalizes a theorem of Cartier.