# On 1-dependent ramsey numbers for graphs

• Volume: 19, Issue: 1, page 93-110
• ISSN: 2083-5892

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## Abstract

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A set X of vertices of a graph G is said to be 1-dependent if the subgraph of G induced by X has maximum degree one. The 1-dependent Ramsey number t₁(l,m) is the smallest integer n such that for any 2-edge colouring (R,B) of Kₙ, the spanning subgraph B of Kₙ has a 1-dependent set of size l or the subgraph R has a 1-dependent set of size m. The 2-edge colouring (R,B) is a t₁(l,m) Ramsey colouring of Kₙ if B (R, respectively) does not contain a 1-dependent set of size l (m, respectively); in this case R is also called a (l,m,n) Ramsey graph. We show that t₁(4,5) = 9, t₁(4,6) = 11, t₁(4,7) = 16 and t₁(4,8) = 17. We also determine all (4,4,5), (4,5,8), (4,6,10) and (4,7,15) Ramsey graphs.

## How to cite

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E.J. Cockayne, and C.M. Mynhardt. "On 1-dependent ramsey numbers for graphs." Discussiones Mathematicae Graph Theory 19.1 (1999): 93-110. <http://eudml.org/doc/270631>.

@article{E1999,
abstract = {A set X of vertices of a graph G is said to be 1-dependent if the subgraph of G induced by X has maximum degree one. The 1-dependent Ramsey number t₁(l,m) is the smallest integer n such that for any 2-edge colouring (R,B) of Kₙ, the spanning subgraph B of Kₙ has a 1-dependent set of size l or the subgraph R has a 1-dependent set of size m. The 2-edge colouring (R,B) is a t₁(l,m) Ramsey colouring of Kₙ if B (R, respectively) does not contain a 1-dependent set of size l (m, respectively); in this case R is also called a (l,m,n) Ramsey graph. We show that t₁(4,5) = 9, t₁(4,6) = 11, t₁(4,7) = 16 and t₁(4,8) = 17. We also determine all (4,4,5), (4,5,8), (4,6,10) and (4,7,15) Ramsey graphs.},
author = {E.J. Cockayne, C.M. Mynhardt},
journal = {Discussiones Mathematicae Graph Theory},
keywords = {1-dependence; irredundance; CO-irredundance; Ramsey numbers; Ramsey number; 1-dependent set; Ramsey colouring; Ramsey graph},
language = {eng},
number = {1},
pages = {93-110},
title = {On 1-dependent ramsey numbers for graphs},
url = {http://eudml.org/doc/270631},
volume = {19},
year = {1999},
}

TY - JOUR
AU - E.J. Cockayne
AU - C.M. Mynhardt
TI - On 1-dependent ramsey numbers for graphs
JO - Discussiones Mathematicae Graph Theory
PY - 1999
VL - 19
IS - 1
SP - 93
EP - 110
AB - A set X of vertices of a graph G is said to be 1-dependent if the subgraph of G induced by X has maximum degree one. The 1-dependent Ramsey number t₁(l,m) is the smallest integer n such that for any 2-edge colouring (R,B) of Kₙ, the spanning subgraph B of Kₙ has a 1-dependent set of size l or the subgraph R has a 1-dependent set of size m. The 2-edge colouring (R,B) is a t₁(l,m) Ramsey colouring of Kₙ if B (R, respectively) does not contain a 1-dependent set of size l (m, respectively); in this case R is also called a (l,m,n) Ramsey graph. We show that t₁(4,5) = 9, t₁(4,6) = 11, t₁(4,7) = 16 and t₁(4,8) = 17. We also determine all (4,4,5), (4,5,8), (4,6,10) and (4,7,15) Ramsey graphs.
LA - eng
KW - 1-dependence; irredundance; CO-irredundance; Ramsey numbers; Ramsey number; 1-dependent set; Ramsey colouring; Ramsey graph
UR - http://eudml.org/doc/270631
ER -

## References

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9. [9] G. MacGillivray, personal communication, 1998.
10. [10] C.M. Mynhardt, Irredundant Ramsey numbers for graphs: a survey, Congr. Numer. 86 (1992) 65-79. Zbl0783.05075
11. [11] S.P. Radziszowski, Small Ramsey numbers, Electronic J. Comb. 1 (1994) DS1.
12. [12] F.P. Ramsey, On a problem of formal logic, Proc. London Math. Soc. 30 (1930) 264-286, doi: 10.1112/plms/s2-30.1.264. Zbl55.0032.04
13. [13] J. Simmons, CO-irredundant Ramsey numbers for graphs, Master's dissertation, University of Victoria, Canada, 1998.
14. [14] Zhou Huai Lu, The Ramsey number of an odd cycle with respect to a wheel, J. Math. - Wuhan 15 (1995) 119-120.

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