proposition: Lemma Urysohn_sub0 (A B : set T) : uniform_separator A B -> Urysohn A B @` A `<=` [set 0].
proof: Proof. by move=> eE; have [_ _ /(_ eE)[]] := projT2 (cid (@Urysohn' A B)). Qed.
imports: HB(structures) mathcomp(all_ssreflect ssralg ssrint ssrnum finmap matrix) mathcomp(rat interval zmodp vector fieldext falgebra) mathcomp(mathcomp_extra boolp classical_sets functions) mathcomp(cardinality set_interval Rstruct) ereal reals signed topology prodnormedzmodule