-- -*- M2-comint -*- {* hash: -464117714 *} i1 : R = QQ[a..d]; i2 : N = coker matrix{{a,b},{c,d}} o2 = cokernel | a b | | c d | 2 o2 : R-module, quotient of R i3 : N1 = N/(a^4*N) o3 = cokernel | a4 0 a b | | 0 a4 c d | 2 o3 : R-module, quotient of R i4 : M = a*N/(R*a*N_0+a*b*N) o4 = subquotient (| a 0 |, | 0 ab 0 a b |) | 0 a | | -c 0 ab c d | 2 o4 : R-module, subquotient of R i5 : isSubquotient(M,N) o5 = true i6 : isSubquotient(M,N1) o6 = false i7 :