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 |