-- -*- M2-comint -*- {* hash: -472007516 *}

i1 : A = QQ[x,y,z];

i2 : M = cokernel matrix(A, {{1,2,3},{4,5,6},{7,8,9}})

o2 = cokernel | 1 2 3 |
              | 4 5 6 |
              | 7 8 9 |

                            3
o2 : A-module, quotient of A

i3 : N = cokernel matrix{{x,y},{z,0}}

o3 = cokernel | x y |
              | z 0 |

                            2
o3 : A-module, quotient of A

i4 : H = Hom(M,N)

o4 = subquotient (| 1  0  |, | y x 0 0 0 0 |)
                  | 0  1  |  | 0 z 0 0 0 0 |
                  | -2 0  |  | 0 0 y x 0 0 |
                  | 0  -2 |  | 0 0 0 z 0 0 |
                  | 1  0  |  | 0 0 0 0 y x |
                  | 0  1  |  | 0 0 0 0 0 z |

                               6
o4 : A-module, subquotient of A

i5 : f = homomorphism H_{0}

o5 = | 1 -2 1 |
     | 0 0  0 |

o5 : Matrix

i6 : target f === N

o6 = true

i7 : source f === M

o7 = true

i8 : matrix f

o8 = | 1 -2 1 |
     | 0 0  0 |

             2       3
o8 : Matrix A  <--- A

i9 :