Fixpoint ielim (x a b c d: tvar) e accu :=
match e with
| nil => accu
| (cc,l) :: e1 =>
ielim x a b c d e1
(inter_elim cc x a b c d l nil accu)
end.

Lemma ielim_c x a b c d e accu:
{v[x]} = ({v[a]} ∨ {v[b]}) ∧({v[c]} ∨ {v[d]}) :> vect K ->
{e[ielim x a b c d e accu]} = ({e[accu]} + {e[e]})%f.