## Abstract We prove that the minimum number of edges in a vertexโdiameterโ2โcritical graph on __n__โโฅโ23 vertices is (5__n__โโโ17)/2 if __n__ is odd, and is (5__n__/2)โโโ7 if __n__ is even. ยฉ 2005 Wiley Periodicals, Inc. J Graph Theory
On vertex critical graphs with prescribed diameter
โ 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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โฆ Synopsis
Abstract
Let G be connected simple graph with diameter d(G). G is said v^+^โcritical if d(Gโv) is greater than d(G) for every vertex v of G. Let Dโฒ = max {d(Gโv) : v โ V(G)}. Boals et al. [Congressus Numerantium 72 (1990), 193โ198] conjectured that if G is a v^+^โcritical graph of diameter D, then Dโฒ โค 2__D__ โ 1. They verified their conjecture for D = 2 and 3. In this paper we show that this conjecture is false for all D โฅ 4 and establish a sharp upper bound for Dโฒ. More specifically, we prove that Dโฒ โค 3D โ 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: 117โ131, 2003
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