proposition: Lemma char_fun_V_bb A x: inc x A -> Vf (char_fun emptyset A) x = \0c.
proof: Proof. move => xa; rewrite char_fun_V_b ? setC_0;fprops. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(binomial div)