fact: Fixpoint DP_ph1_aux (d: (list (list bool))) := if d is l::d then DP_ph1_aux d && [|| size l == 2, nilp d | size (head nil d) == 2] else true.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype) mathcomp(ssrnat seq path div) mathcomp(fintype tuple finfun bigop finset binomial)