Degenerate Principal Series 7
THEOREM 1.2.4 (Bernstein-Zelevinsky, Casselman) Let p be an admissible rep-
resentation of M. Then, r^o ° iGMP has a composition series with factors
iNN owo rM'Mp, w € WMN
where M' = M H w'1(N), N' = w(M) n N.
Proof See [Cas2], chapter 6 or [B-Z2] "geometrical lemma" (Lemma 2.12), proved
in chapter 6.