Section CBDistrLattice.
Variables (n : nat) (T : cbDistrLatticeType disp).
Implicit Types (t : n.-tuple T).
Definition sub t1 t2 : n.-tuple T :=
[tuple of [seq x.1 `\` x.2 | x <- zip t1 t2]].
Fact tnth_sub t1 t2 i : tnth (sub t1 t2) i = tnth t1 i `\` tnth t2 i.

Lemma joinIB t1 t2 : t1 `&` t2 `|` sub t1 t2 = t1.