--Deux petites fonctions utiles pour calculer un mineur maximal MaxCol = (M) -> ( --M is matrix in a Polynomial Ring --MaxCol returns a submatrix of M with rank M col, of rank M, --using generic substitution. Aring:=ring M; lm:=rank target M; cm:=rank source M; l:={}; i:=0; while i ( --Apply two times MaxCol to obtain a maximal minor --This is not very efficient... return(transpose MaxCol(transpose MaxCol(M))) );