fact: Definition valid_ctrm (cm : bitseq) cp := let n := count id cm in if n == 4 then cptriad (ctrband cm cp) cp (cpksize cp) else 0 < n <= 3.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype path fingraph) fourcolor(hypermap geometry color coloring cfmap ctree) fourcolor(cfcolor)