rewrite expand_meetl.
rewrite sub_add, meet_addl.
rewrite !meet_scall.
pattern (x2 ∧ x5 ∨ x6) at 1; rewrite <- join1l.
rewrite bracket_swapr, bracket_swapl; Krm1.
rewrite <-join_scall, <-bracket_defl.
pattern (x1 ∧ x5 ∨ x6) at 1; rewrite <- join1l.
rewrite bracket_swapr, bracket_swapl; Krm1.
rewrite <-join_scall, <-bracket_defl; auto.
Qed.

Lemma split_meetr (x1 x2 x3 x4 x5 x6: point) :
((x1 ∨ x2) ∧ (x3 ∨ x4)) ∧ (x5 ∨ x6) =
((x1 ∨ x2) ∧ x5) ∨ ((x3 ∨ x4) ∧ x6) +
(-(1))%f .* ((x3 ∨ x4) ∧ x5) ∨ ((x1 ∨ x2) ∧ x6).