(* Some view lemmas for processes and corresponding schedules *)

Lemma stepSeq W A B s1 (t : proc this W B) k sc s2 (q : proc this W A) :
pstep s1 (Seq t k) sc s2 q <->
(exists v, [/\ sc = SeqRet, t = Ret v, q = k v, s2 = s1 &
s1 \In Coh W]) \/
exists sc' p',
[/\ sc = SeqStep sc', q = Seq p' k & pstep s1 t sc' s2 p'].