-- -*- M2-comint -*- {* hash: 1216967616 *}

i1 : R = ZZ[a..d];

i2 : M = cokernel matrix{{2*a-b,3*c-5*d,a^2-b-3}}

o2 = cokernel | 2a-b 3c-5d a2-b-3 |

                            1
o2 : R-module, quotient of R

i3 : f = map(a*M, M, a^3+a^2*b)

o3 = {1} | a+10b+18 |

o3 : Matrix

i4 : (target f,source f)

o4 = (subquotient (| a |, | 2a-b 3c-5d a2-b-3 |), cokernel | 2a-b 3c-5d
     ------------------------------------------------------------------------
     a2-b-3 |)

o4 : Sequence

i5 : N = cokernel f

o5 = subquotient (| a |, | a2+10ab+18a 2a-b 3c-5d a2-b-3 |)

                               1
o5 : R-module, subquotient of R

i6 : minimalPresentation N

o6 = cokernel | 3c-5d 3b-18 21b+36 a+10b+18 b2-4b-12 |

                            1
o6 : R-module, quotient of R

i7 :