?? try naive "explicit" approach to "green substitution" ?? ...

?? q-analog of "take set, split into pieces, put structure of type t1 on each piece, of type t2 on set of pieces" ..... ????? ....

?? "take f_q-vsp, put partial flag on it, put type t1 structure on each grade, and put type t2 structure on ?????? of grades" ??????????? ...... ??????? .......

?? "parabolic induction" .... ???? ....