proposition: Lemma bet_symmetry : bet_symmetryP Point bet'.
proof: Proof. move => a b c /andP[H1 H2]; apply /andP; split; by rewrite bet_sym. Qed.
imports: mathcomp.ssreflect.ssreflect mathcomp(ssrbool ssrfun ssrnat eqtype choice seq) mathcomp(fintype finset finfun bigop order) mathcomp(ssralg ssrnum path generic_quotient matrix mxalgebra) mathcomp(zmodp) GeoCoq.Meta_theory.Models.POF_to_Tarski GeoCoq.Meta_theory.Counter_models.Planar.independence