# A maximum degree theorem for diameter-2-critical graphs

Open Mathematics (2014)

• Volume: 12, Issue: 12, page 1882-1889
• ISSN: 2391-5455

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## Abstract

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A graph is diameter-2-critical if its diameter is two and the deletion of any edge increases the diameter. Let G be a diameter-2-critical graph of order n. Murty and Simon conjectured that the number of edges in G is at most ⌊n 2/4⌋ and that the extremal graphs are the complete bipartite graphs K ⌊n/2⌋,⌊n/2⌉. Fan [Discrete Math. 67 (1987), 235–240] proved the conjecture for n ≤ 24 and for n = 26, while Füredi [J. Graph Theory 16 (1992), 81–98] proved the conjecture for n > n 0 where n 0 is a tower of 2’s of height about 1014. The conjecture has yet to be proven for other values of n. Let Δ denote the maximum degree of G. We prove the following maximum degree theorems for diameter-2-critical graphs. If Δ ≥ 0.7 n, then the Murty-Simon Conjecture is true. If n ≥ 2000 and Δ ≥ 0.6789 n, then the Murty-Simon Conjecture is true.

## How to cite

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Teresa Haynes, et al. "A maximum degree theorem for diameter-2-critical graphs." Open Mathematics 12.12 (2014): 1882-1889. <http://eudml.org/doc/268952>.

@article{TeresaHaynes2014,
abstract = {A graph is diameter-2-critical if its diameter is two and the deletion of any edge increases the diameter. Let G be a diameter-2-critical graph of order n. Murty and Simon conjectured that the number of edges in G is at most ⌊n 2/4⌋ and that the extremal graphs are the complete bipartite graphs K ⌊n/2⌋,⌊n/2⌉. Fan [Discrete Math. 67 (1987), 235–240] proved the conjecture for n ≤ 24 and for n = 26, while Füredi [J. Graph Theory 16 (1992), 81–98] proved the conjecture for n > n 0 where n 0 is a tower of 2’s of height about 1014. The conjecture has yet to be proven for other values of n. Let Δ denote the maximum degree of G. We prove the following maximum degree theorems for diameter-2-critical graphs. If Δ ≥ 0.7 n, then the Murty-Simon Conjecture is true. If n ≥ 2000 and Δ ≥ 0.6789 n, then the Murty-Simon Conjecture is true.},
author = {Teresa Haynes, Michael Henning, Lucas Merwe, Anders Yeo},
journal = {Open Mathematics},
keywords = {Diameter critical; Diameter-2-critical; Total domination critical; diameter critical; diameter-2-critical; total domination critical},
language = {eng},
number = {12},
pages = {1882-1889},
title = {A maximum degree theorem for diameter-2-critical graphs},
url = {http://eudml.org/doc/268952},
volume = {12},
year = {2014},
}

TY - JOUR
AU - Teresa Haynes
AU - Michael Henning
AU - Lucas Merwe
AU - Anders Yeo
TI - A maximum degree theorem for diameter-2-critical graphs
JO - Open Mathematics
PY - 2014
VL - 12
IS - 12
SP - 1882
EP - 1889
AB - A graph is diameter-2-critical if its diameter is two and the deletion of any edge increases the diameter. Let G be a diameter-2-critical graph of order n. Murty and Simon conjectured that the number of edges in G is at most ⌊n 2/4⌋ and that the extremal graphs are the complete bipartite graphs K ⌊n/2⌋,⌊n/2⌉. Fan [Discrete Math. 67 (1987), 235–240] proved the conjecture for n ≤ 24 and for n = 26, while Füredi [J. Graph Theory 16 (1992), 81–98] proved the conjecture for n > n 0 where n 0 is a tower of 2’s of height about 1014. The conjecture has yet to be proven for other values of n. Let Δ denote the maximum degree of G. We prove the following maximum degree theorems for diameter-2-critical graphs. If Δ ≥ 0.7 n, then the Murty-Simon Conjecture is true. If n ≥ 2000 and Δ ≥ 0.6789 n, then the Murty-Simon Conjecture is true.
LA - eng
KW - Diameter critical; Diameter-2-critical; Total domination critical; diameter critical; diameter-2-critical; total domination critical
UR - http://eudml.org/doc/268952
ER -

## References

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