This function takes as input a matrix
m with linear entries, which we think of as a presentation matrix for a positively graded
S-module
M matrix representing the map
M_1 ** omega_E <-- M_0 ** omega_E which is the first differential of the complex
R(M).
i1 : S = ZZ/32003[x_0..x_2];
|
i2 : E = ZZ/32003[e_0..e_2, SkewCommutative=>true];
|
i3 : M = coker matrix {{x_0^2, x_1^2}};
|
i4 : m = presentation truncate(regularity M,M);
4 8
o4 : Matrix S <--- S
|
i5 : symExt(m,E)
o5 = {-1} | e_2 e_1 e_0 0 |
{-1} | 0 e_2 0 e_0 |
{-1} | 0 0 e_2 e_1 |
{-1} | 0 0 0 e_2 |
4 4
o5 : Matrix E <--- E
|