Table of the largest known graphs of a given diameter and maximal degree

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In graph theory, the degree diameter problem is the problem of finding the largest possible graph for a given maximum degree and diameter. The Moore bound sets limits on this, but for many years mathematicians in the field have been interested in a more precise answer. The table below gives current progress on this problem (excluding the case of degree 2, where the largest graphs are cycles with an odd number of vertices).

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Table of the orders of the largest known graphs for the undirected degree diameter problem

Below is the table of the vertex numbers for the best-known graphs (as of June 2024) in the undirected degree diameter problem for graphs of degree at most 3 ≤ d ≤ 16 and diameter 2 ≤ k ≤ 10. Only a few of the graphs in this table (marked in bold) are known to be optimal (that is, largest possible). The remainder are merely the largest so far discovered, and thus finding a larger graph that is closer in order (in terms of the size of the vertex set) to the Moore bound is considered an open problem. Some general constructions are known for values of d and k outside the range shown in the table.

k
d
2345678910
310 [g 1] 20 [g 2] 38 [g 3] 70 [g 4] 132 [g 5] 196 [g 5] 360 [g 6] 600 [g 5] 1250 [g 7]
415 [g 2] 41 [g 8] 98 [g 5] 364 [g 9] 740 [g 10] 1 3203 2437 57517 703
524 [g 2] 72 [g 5] 212 [g 5] 6242 772 [g 11] 5 51617 03057 840187 056
632 [g 12] 111 [g 5] 39014047 917 [g 11] 19 38376 891 [g 13] 331 387 [g 14] 1 253 615
750 [g 15] 168 [g 5] 672 [g 16] 2 756 [g 17] 12 264 [g 13] 53 020 [g 13] 249 6601 223 0506 007 230
857 [g 18] 253 [g 19] 1 1005 115 [g 13] 39 672 [g 20] 131 137734 8204 243 10024 897 161
974 [g 18] 585 [g 9] 1 640 [g 13] 8 268 [g 14] 75 893 [g 11] 279 6161 697 688 [g 14] 12 123 28865 866 350
1091 [g 18] 650 [g 9] 2 331 [g 13] 13 203 [g 13] 134 690 [g 20] 583 0834 293 45227 997 191201 038 922
11104 [g 5] 715 [g 9] 3 200 [g 21] 19 620 [g 13] 156 864 [g 21] 1 001 2687 442 32872 933 102600 380 000
12133 [g 22] 786 [g 20] 4 680 [g 23] 29 621 [g 13] 359 772 [g 11] 1 999 50015 924 326158 158 8751 506 252 500
13162 [g 24] 856 [g 25] 6 560 [g 21] 40 488 [g 13] 531 440 [g 21] 3 322 08029 927 790249 155 7603 077 200 700
14183 [g 22] 916 [g 20] 8 200 [g 21] 58 095 [g 13] 816 294 [g 11] 6 200 460 [g 26] 55 913 932600 123 7807 041 746 081
15187 [g 27] 1 215 [g 28] 11 712 [g 21] 77 520 [g 13] 1 417 248 [g 21] 8 599 98690 001 2361 171 998 16410 012 349 898
16200 [g 29] 1 600 [g 28] 14 640 [g 21] 132 496 [g 28] 1 771 560 [g 21] 14 882 658 [g 26] 140 559 4162 025 125 47612 951 451 931

Entries without a footnote were found by Loz & Širáň (2008). In all other cases, the footnotes in the table indicate the origin of the graph that achieves the given number of vertices:

  1. ↑ The Petersen graph.
  2. 1 2 3 Optimal graphs proven optimal by Elspas (1964).
  3. ↑ Optimal graph found by Doty (1982) and proven optimal by Buset (2000).
  4. ↑ Graph found by Alegre, Fiol & Yebra (1986).
  5. 1 2 3 4 5 6 7 8 9 Graphs found by Geoffrey Exoo from 1998 through 2010.
  6. ↑ Graph found by Jianxiang Chen in 2018.
  7. ↑ Graph found by Conder (2006).
  8. ↑ Graph found by Allwright (1992).
  9. 1 2 3 4 Graphs found by Delorme (1985a).
  10. ↑ Graph found by Comellas & Gómez (1994).
  11. 1 2 3 4 5 Graphs found by Pineda-Villavicencio et al. (2006).
  12. ↑ Optimal graph found by Wegner (1977) and proven optimal by Molodtsov (2006).
  13. 1 2 3 4 5 6 7 8 9 10 11 12 Graphs found by Comellas (2024).
  14. 1 2 3 Graphs found by Canale & Rodríguez (2012).
  15. ↑ The Hoffman–Singleton graph.
  16. ↑ Graph found by Sampels (1997).
  17. ↑ Graph found by Dinneen & Hafner (1994).
  18. 1 2 3 Graphs found by Storwick (1970).
  19. ↑ Graph found by Margarida Mitjana and Francesc Comellas in 1995, and independently by Sampels (1997).
  20. 1 2 3 4 Graphs found by Gómez (2009).
  21. 1 2 3 4 5 6 7 8 9 Graphs found by Gómez & Fiol (1985).
  22. 1 2 Graphs found by Delorme & Farhi (1984).
  23. ↑ Graph found by Bermond, Delorme & Farhi (1982).
  24. ↑ McKay–Miller–Širáň graphs found by McKay, Miller & Širáň (1998).
  25. ↑ Graph found by Vlad Pelakhaty in 2021.
  26. 1 2 Graphs found by Gómez, Fiol & Serra (1993).
  27. ↑ Graph found by Eduardo A. Canale in 2012.
  28. 1 2 3 Graphs found by Delorme (1985b).
  29. ↑ Graph found by Abas (2016).

References

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