proposition: Corollary eqsl_uxox (ks : seq A) t1 t2 : t1 <=[ks] t2 -> &=ks `]-oo, t2] = &=ks `]-oo, t1] ++ &=ks `]t1, t2].
proof: Proof. by move=>H; apply: eqslice_split. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path interval order) pcm(options prelude ordtype seqext slice useqord)