The Kirchhoff index ,
also simply called the resistance and denoted
(Lukovits et al. 1999), of a finite connected
graph
on
nodes is defined by
where
is the resistance distance matrix.
Unless otherwise stated, hydrogen atoms are usually ignored in the computation of such indices as organic chemists usually do when they write a benzene ring as a hexagon (Devillers and Balaban 1999, p. 25).
Precomputed values for many graphs are implemented in the Wolfram Language as GraphData[g, "KirchhoffIndex"].
The following table summarizes values of the Kirchhoff index for various special classes of graphs. The index of each value list in the
table starts at 1. An X indicates that the family in that row is not defined for
the corresponding parameter value or has no value in the domain of connected
graphs. In the tables, crossed prism graphs
are parametrized by a cycle size of . The sun graph row uses the
complete
-sun
convention.
| graph class | OEIS | |
| Andrásfai graph | 1, 10, 134/7, 3080/109, 263599/7059, 5244806/113017, ... | |
| antiprism graph | X, X, 13/2, 290/21, 551/22, 41, ... | |
| Apollonian network | 3, 834/85, 30154/475, 23555722/44125, 1259601793/263125, ... | |
| cocktail
party graph | ||
| complete
bipartite graph | 1, 5, 9, 13, 17, 21, 25, 29, 33, 37, ... | |
| complete graph | A001477 | 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, ... |
| complete tripartite graph | 2, 13/2, 11, 31/2, 20, 49/2, ... | |
| crossed
prism graph with cycle size | X, 58/3, 53, 332/3, 595/3, 322, 1463/3, 2104/3, 969, 3890/3, ... | |
| crown graph | X, X, 35/2, 58/3, 271/12, 131/5, 899/30, 710/21, ... | |
| cube-connected cycle graph | X, X, 346, 6442544/2415, 33760334655251468654052195628373/1958536428315956487415847430, ... | |
| cycle graph | A138190/A138191 | X, X, 2, 5, 10, 35/2, 28, 42, ... |
| folded cube graph | X, 1, 3, 13, 50, 548/3, 1960/3, 6968/3, 8272, ... | |
| gear graph | X, X, 18, 69/2, 1085/19, 257/3, 8526/71, 6733/42, 10935/53, 53945/209, ... | |
| grid graph | 0, 5, 69/2, 884/7, 11155/33, 535131/715, 47274465/32422, 111014696336/42859159, ... | |
| grid graph | 0, 58/3, 16959/70, 489296/357, 119593165825/23110593, 3959047278723/259814555, ... | |
| halved cube graph | A290165/A290366 | 0, 1, 3, 25/3, 70/3, 3014/45, 2968/15, 63148/105, 197072/105, ... |
| hypercube graph | A290343/A290344 | 1, 5, 58/3, 206/3, 3548/15, ... |
| Möbius
ladder | X, X, 9, 134/7, 1135/33, 725/13, 10367/123, 11732/97, 2835/17, ... | |
| Mycielski graph | 0, 1, 10, 4545/139, 8808777389/93842615, ... | |
| odd graph | 0, 2, 33, 373, 4000, 264001/6, ... | |
| pan graph | X, X, 19/3, 23/2, 19, 88/3, 43, ... | |
| path graph | 0, 1, 4, 10, 20, 35, 56, 84, 120, 165, ... | |
| permutation star graph | 0, 1, 35/2, 1314/5, 26520, 963598/7, ... | |
| prism
graph | X, X, 47/5, 58/3, 655/19, 279/5, ... | |
| rook graph | 0, 5, 18, 42, 80, 135, 210, 308, 432, ... | |
| star
graph | A000290 | 0, 1, 4, 9, 16, 25, 36, 49, 64, 81, ... |
| sun graph | X, X, 65/6, 302/15, 1955/62, 1169/26, 74543/1234, 188044/2415, 3606873/37058, 16594610/139683, 213092209/1497718, ... | |
| sunlet graph | X, X, 23, 48, 85, 136, 203, 288, 393, 520, 671, ... | |
| tetrahedral graph | X, X, X, X, X, 43, 207/2, 1945/9, 4901/12, 2149/3, ... | |
| triangular graph | X, 0, 2, 13/2, 57/4, 26, 85/2, 129/2, 371/4, 128, ... | |
| web graph | X, X, 222/5, 173/2, 2780/19, 4521/20, 23282/71, 3179/7, 160848/265, ... | |
| wheel graph | X, X, X, 16/3, 95/11, 129/10, ... |
Closed forms are summarized in the following table. The cycle graph was considered by Klein et al.
(1995) and Babić et al. (2002). The hypercube
graph formula uses the binomial coefficient . For disconnected
graphs, the displayed value
is an extension by convention.
| graph | |
| cocktail
party graph | |
| complete bipartite
graph | |
| complete graph | |
| complete
tripartite graph | |
| crossed prism graph
with cycle size | |
| crown graph with | |
| cycle graph | |
| empty graph | |
| hypercube graph | |
| pan graph with | |
| path graph | |
| rook
graph | |
| star graph | |
| triangular
graph with |