proposition: Fact joinKI t2 t1 : meet t1 (join t1 t2) = t1.
proof: Proof. by apply: eq_from_tnth => i; rewrite tnth_meet tnth_join joinKI. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)