intuition.
eapply evalDet_steps_bind_done_inv_h; eauto.
Qed.

Theorem evalDet_steps_bind_eof_inv_h :
forall (A : Set)(x y : comp_state A),
evalDet_steps x y ->
forall (B : Set)(c1 : Comp B)(c2 : B -> Comp A) s,
x = (cs_more (Bind c1 c2) s) ->
y = (@cs_eof A) ->
evalDet_steps (cs_more c1 s) (@cs_eof B) \/
exists b s', evalDet_steps (cs_more c1 s) (cs_done b s') /\
evalDet_steps (cs_more (c2 b) s') (@cs_eof A).