Extensions of strict polynomial functors
Extensions of strict polynomial functors
We compute Ext-groups between Frobenius twists of strict polynomial functors. The main result concerns the groups ExtP∗(Dd(i),F(i)) where Dd is the divided power functor, and F is an arbitrary functor. These groups are shown to be isomorphic to F(Ai) for certain explicitly described graded space Ai. We also calculate the …