proposition: Lemma Ex6_32p3' n f: intp n -> cardinalp (f (BZsucc n)) -> f (BZsucc n) <=c csumb (ZN_int n \0c \1c) f.
proof: Proof. by move => ha hb; rewrite (Ex6_32p2 _ ha); apply: csum_Mle0. Qed.
imports: mathcomp(ssreflect ssrbool ssrfun eqtype)