Abstract
Given a connected edge-regular graph Γ with parameters (v, k, λ) and b 1 = k − λ − 1, we prove that in the case k ≥ 3b 1 −2 either |Γ2(u)|(k−2b 1 + 2) < kb 1 for every vertex u or Γ is a polygon, the edge graph of a trivalent graph without triangles that has diameter greater than 2, the icosahedral graph, the complete multipartite graph K r×2, the 3 × 3-grid, the triangular graph T(m) with m ≤ 7, the Clebsch graph, or the Schläfli graph.
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Brouwer A. E., Cohen A. M., and Neumaier A., Distance-Regular Graphs, Springer-Verlag, Berlin (1989).
Makhnev A. A., Vedenev A. A., Kuznetsov A. N., and Nosov V. V., “On good pairs in edge-regular graphs,” Diskret. Mat., 15, No. 1, 77–97 (2003).
Makhnev A. A., “On extensions of the partial geometries with small μ-subgraphs,” Diskret. Anal. Issled. Oper., 3, No. 3, 71–83 (1996).
Makhnev A. A., “On the strong regularity of some edge-regular graphs,” Izv. Math., 68, No. 6, 159–180 (2004).
Belousov I. N. and Makhnev A. A., “On almost good pairs of edges in edge-regular graphs. On extensions of the partial geometries with small μ-subgraphs,” Izv. Ural State Univ., 36, 35–48 (2005).
Makhnev A. A. and Minakova I. M., “On one class of edge-regular graphs,” Izv. Gomel State Univ. Voprosy Algebry, 3, 145–154 (2000).
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Translated from Sibirskiĭ Matematicheskiĭ Zhurnal, Vol. 48, No. 4, pp. 817–832, July–August, 2007.
Original Russian Text Copyright © 2007 Makhnev A. A. and Paduchikh D. V.
The authors were supported by the Russian Foundation for Basic Research (Grant 05-01-00046) and RFFI-GFEN (Grant 05-01-39000).
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Makhnev, A.A., Paduchikh, D.V. A new estimate for the vertex number of an edge-regular graph. Sib Math J 48, 653–665 (2007). https://doi.org/10.1007/s11202-007-0067-4
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DOI: https://doi.org/10.1007/s11202-007-0067-4