Restrictions of modules over classical groups to subgroups of type A _1 × A _1 in characteristic 2

摘要

The restrictions of irreducible modules over classical groups in characteristic 2 to subsystem subgroups of type A _1 × A _1 are studied. The composition factors (without their multiplicities) for restrictions of irreducible modules over A _r(K) and D _r(K) with 2-restricted highest weights are found.