\(\text{Ext}^ 1\) for Weyl modules of \(\text{SL}_ 2(K)\)
Let \(G = \text{SL}_ 2 (K)\) where \(K\) is an algebraically closed field of characteristic \(p\). Let \(\Delta (\lambda)\) be the Weyl module of \(G\) with highest weight \(\lambda\). We determine \(\text{Ext}^ 1_ G (\Delta (\lambda), \Delta (\mu))\) for arbitrary \(\lambda\) and \(\mu\). In particular we show that the dimension is at most 1.
scientific article; zbMATH DE number 778956