fact: Definition pminor (m n p : nat) (h : p < m) (h' : p < n) (A : 'M[R]_(m,n)) := minor (widen_ord h) (widen_ord h') A.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq path ssralg) mathcomp(fintype perm choice finfun matrix bigop zmodp poly mxpoly)