Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4650614 | Discrete Mathematics | 2006 | 9 Pages |
Abstract
Let n be a positive integer. A tournament is called n-existentially closed (or n-e.c.) if for every subset S of n vertices and for every subset T of SS, there is a vertex x∉Sx∉S which is directed toward every vertex in T and directed away from every vertex in S⧹TS⧹T. We prove that there is a 2-e.c. tournament with k vertices if and only if k≥7k≥7 and k≠8k≠8, and give explicit examples for all such orders k. We also give a replication operation which preserves the 2-e.c. property.
Keywords
Related Topics
Physical Sciences and Engineering
Mathematics
Discrete Mathematics and Combinatorics
Authors
Anthony Bonato, Kathie Cameron,