fact: Definition same_codom m n (f g: {ffun 'I_m -> 'I_n}) := forall x, (x \in codom f) = (x \in codom g).
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq path) mathcomp(ssralg fintype perm choice finfun) mathcomp(matrix bigop zmodp mxalgebra fingroup) minor