TWISTED LEVI SEQUENCES AND EXPLICIT TYPES ON Sp4

Let G be a connected reductive group over a field F. A twisted Levi subgroup G ′ of G is a reductive subgroup such that G ′ ⊗F F is a Levi subgroup of G ⊗F F. Twisted Levi subgroups have been an important tool in studying the structure theory of representations of p-adic groups. For example, supercuspidal representations are built out of certain representations of twisted Levi subgroups ([20])