-- -*- M2-comint -*- {* hash: 1933255388 *}

i1 : R = ZZ/101[a..d]

o1 = R

o1 : PolynomialRing

i2 : M = kernel vars R ++ cokernel vars R

o2 = subquotient ({1} | -b 0  -c 0  0  -d 0 |, {1} | 0 0 0 0 |)
                  {1} | a  -c 0  0  -d 0  0 |  {1} | 0 0 0 0 |
                  {1} | 0  b  a  -d 0  0  0 |  {1} | 0 0 0 0 |
                  {1} | 0  0  0  c  b  a  0 |  {1} | 0 0 0 0 |
                  {0} | 0  0  0  0  0  0  1 |  {0} | a b c d |

                               5
o2 : R-module, subquotient of R

i3 : generators M

o3 = {1} | -b 0  -c 0  0  -d 0 |
     {1} | a  -c 0  0  -d 0  0 |
     {1} | 0  b  a  -d 0  0  0 |
     {1} | 0  0  0  c  b  a  0 |
     {0} | 0  0  0  0  0  0  1 |

             5       7
o3 : Matrix R  <--- R

i4 : relations M

o4 = {1} | 0 0 0 0 |
     {1} | 0 0 0 0 |
     {1} | 0 0 0 0 |
     {1} | 0 0 0 0 |
     {0} | a b c d |

             5       4
o4 : Matrix R  <--- R

i5 : M === subquotient(generators M, relations M)

o5 = true

i6 : prune M,

o6 = (cokernel {2} | 0 0 0 0 c  0  0  d  |, )
               {2} | 0 0 0 0 a  d  0  0  |
               {2} | 0 0 0 0 -b 0  d  0  |
               {2} | 0 0 0 0 0  b  a  0  |
               {2} | 0 0 0 0 0  -c 0  a  |
               {2} | 0 0 0 0 0  0  -c -b |
               {0} | d c b a 0  0  0  0  |

o6 : Sequence

i7 :