We compute the Hankel matrices over the Cox ring, which give rize to the relative quadrics of a degenerate K3 Xe(a,b) in case of k resonance within the resonance scroll, compare with the proof of Theorem 4.12 of [ES18].
i1 : (A,B,A1,B1)=coxMatrices(6,5,4); |
i2 : A,A1
o2 = (| u_0 u_1 su_2 u_3 |, | u_0 su_1 su_2 |)
| u_1 u_2 u_3 tu_0 | | u_1 su_2 u_3 |
| u_2 u_3 tu_0 |
o2 : Sequence
|
i3 : B,B1
o3 = (| v_0 sv_1 v_2 v_3 |, | sv_0 sv_1 v_2 |)
| v_1 v_2 v_3 tv_0 | | sv_1 v_2 v_3 |
| v_2 v_3 tv_0 |
o3 : Sequence
|
i4 : (A,B,A1,B1)=coxMatrices(7,4,4); |
i5 : A,A1
o5 = (| u_0 u_1 u_2 su_3 |, | u_0 u_1 su_2 |)
| u_1 u_2 u_3 tu_0 | | u_1 u_2 su_3 |
| u_2 u_3 tu_0 |
o5 : Sequence
|
i6 : B,B1
o6 = (| sv_0 v_1 v_2 v_3 |, | sv_0 v_1 v_2 |)
| v_1 v_2 v_3 tv_0 | | v_1 v_2 v_3 |
| v_2 v_3 tv_0 |
o6 : Sequence
|