This symmetric matrix has entries k(i,i) along the diagonal and entry k(i,j) in the (i,j) position if there is an edge between i and j, and a zero otherwise. The documentation of gaussianRing further describes the indeterminates k(i,j).
i1 : G = graph({{a,b},{b,c},{c,d},{a,d}})
o1 = Graph{a => set {b, d}}
b => set {a, c}
c => set {b, d}
d => set {a, c}
o1 : Graph
|
i2 : R = gaussianRing G o2 = R o2 : PolynomialRing |
i3 : compactMatrixForm =false; |
i4 : K = undirectedEdgesMatrix(R)
o4 = | k k 0 k |
| a,a a,b a,d |
| |
| k k k 0 |
| a,b b,b b,c |
| |
| 0 k k k |
| b,c c,c c,d |
| |
| k 0 k k |
| a,d c,d d,d |
4 4
o4 : Matrix R <--- R
|