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On vertex critical graphs with prescribed diameter

โœ Scribed by L. Caccetta; S. EL-Batanouny; J. Huang


Publisher
John Wiley and Sons
Year
2003
Tongue
English
Weight
167 KB
Volume
43
Category
Article
ISSN
0364-9024

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โœฆ Synopsis


Abstract

Let G be connected simple graph with diameter d(G). G is said v^+^โ€critical if d(Gโˆ’v) is greater than d(G) for every vertex v of G. Let Dโ€ฒ = max {d(Gโˆ’v) : v โˆˆ V(G)}. Boals et al. [Congressus Numerantium 72 (1990), 193โ€”198] conjectured that if G is a v^+^โ€critical graph of diameter D, then Dโ€ฒ โ‰ค 2__D__ โˆ’ 1. They verified their conjecture for D = 2 and 3. In this paper we show that this conjecture is false for all D โ‰ฅ 4 and establish a sharp upper bound for Dโ€ฒ. More specifically, we prove that Dโ€ฒ โ‰ค 3D โˆ’ 3 for D = 4, 6, 8; and $D^\prime \le 2D + 3 \left\lfloor {{1 \over 2}(D + 1)} \right\rfloor! - 8$; otherwise. ยฉ 2003 Wiley Periodicals, Inc. J Graph Theory 43: 117โ€“131, 2003


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