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.

(* Specifications: *)
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).
Lemma meet_swapr (x y x1 y1: point) :
(x ∨ x1) ∧ (y ∨ y1) = (x1 ∨ x) ∧ (y1 ∨ y).
Lemma join_meet3l (a b c d e f: point) :
(a ∨ b) ∨ ((c ∨ d) ∧ (e ∨ f)) = ((a ∨ b) ∧ (c ∨ d) ∧ (e ∨ f)) ∨ E.
Lemma join_meet3r (a b c d e f: point) :
((a ∨ b) ∧ (c ∨ d)) ∨ (e ∨ f) = ((a ∨ b) ∧ (c ∨ d) ∧ (e ∨ f)) ∨ E.
Lemma split3l (a b c d : point) :
(a ∨ b ∨ c) ∧  d = '[b,c,d] .* a - '[a,c,d] .* b + '[a,b,d] .* c.