منابع مشابه
Disjoint Directed Cycles
It is shown that there exists a positive so that for any integer k, every directed graph with minimum outdegree at least k contains at least k vertex disjoint cycles. On the other hand, for every k there is a digraph with minimum outdegree k which does not contain two vertex or edge disjoint cycles of the same length.
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Let D be a directed graph of order n 4 and minimum degree at least (3n 3)/2. Let n = nI + n2 where nl 2 and n2 2. Then D contains two vertex-disjoint directed cycles of nI and n2 respectively. The result is sharp if n ~ 6: we give counterexamples if the condition on the minimum degree is relaxed. 1 Introduction We discuss only finite simple graphs and strict and use standard terminology and not...
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6 The dicycle transversal number τ(D) of a digraph D is the mini7 mum size of a dicycle transversal of D, i. e. a set T ⊆ V (D) such that 8 D − T is acyclic. We study the following problem: Given a digraph D, 9 decide if there is a dicycle B in D and a cycle C in its underlying undi10 rected graph UG(D) such that V (B)∩V (C) = ∅. It is known that there is 11 a polynomial time algorithm for this...
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ژورنال
عنوان ژورنال: Journal of Combinatorial Theory, Series B
سال: 1996
ISSN: 0095-8956
DOI: 10.1006/jctb.1996.0062