Abstract

A (3,k,n,e) Ramsey graph is a triangle-free graph on n vertices with e edges and no independent set of size k. Similarly, a (3,k)-, (3,k,n)- or (3,k,n,e)-graph is a (3,k,n,e) Ramsey graph for some nand e. In the first part of the paper we derive an explicit formula for the minimum number of edges in any (3,k,n)graph for n ≤ 3(k-I), i.e. a partial formula for the function e(3,k,n) investigated in [3,5,7]. We prove some general properties of minimum (3,k,n)- graphs with e(3,k,n) edges and present a construction of minimum (3,k+I,3k-I,5k-5)-graphs for k ≥ 2 and minimum (3,k+1,3k,5k)-graphs for k ≥ 4. In the second part of the paper we describe a catalogue of small Ramsey graphs: all (3,k)-graphs for k ~6 and some (3,7)-graphs including all 191 (3,7,22)-graphs, produced by a computer. We present for k ≤ 7 all minimum (3,k,n)-graphs and all 10 maximum (3,7,22)-graphs with 66 edges. *Please refer to full-text for correct equations and numerical values

Publication Date

1988

Comments

Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works in February 2014.

Document Type

Article

Department, Program, or Center

Center for Advancing the Study of CyberInfrastructure

Campus

RIT – Main Campus

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