Tournaments as strong subcontractions
نویسندگان
چکیده
منابع مشابه
Strong subtournaments of multipartite tournaments
An orientation of a complete graph is a tournament, and an orientation of a complete n-partite graph is an n-partite tournament. For each n 2:: 4, there exist examples of strongly connected n-partite tournament without any strongly connected subtournaments of order p 2:: 4. If D is a digraph, then let d+ (x) be the out degree and d(x) the indegree of the vertex x in D. The minimum (maximum) out...
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The pattern of a matrix M is a (0, 1)-matrix which replaces all non-zero entries of M with a 1. A directed graph is said to support M if its adjacency matrix is the pattern of M . If M is an orthogonal matrix, then a digraph which supports M must satisfy a condition known as quadrangularity. We look at quadrangularity in tournaments and determine for which orders quadrangular tournaments exist....
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We examine the size s(n) of a smallest tournament having the arcs of an acyclic tournament on n vertices as a minimum feedback arc set. Using an integer linear programming formulation we obtain lower bounds s(n) ≥ 3n − 2 − blog2 nc or s(n) ≥ 3n − 1 − blog2 nc, depending on the binary expansion of n. When n = 2k − 2t we show that the bounds are tight with s(n) = 3n−2−blog2 nc. One view of this p...
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An arc in a tournament T with n ≥ 3 vertices is called k-pancyclic, if it belongs to a cycle of length l for all k ≤ l ≤ n. In this paper, the result that each s-strong (s ≥ 3) tournament T contains at least s + 2 out-arc 5-pancyclic vertices is obtained. Furthermore, our proof yields a polynomial algorithm to find s + 2 out-arc 5-pancyclic vertices of T .
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ژورنال
عنوان ژورنال: Discrete Mathematics
سال: 1997
ISSN: 0012-365X
DOI: 10.1016/s0012-365x(97)81803-1