A Group Theoretical Approach to Disjoint Paths in Directed Graphs
نویسنده
چکیده
This is in general a hard problem The problem is NP complete Knuth cf even if we restrict ourselves to planar undirected graphs Lynch assuming that k is variable On the other hand it is a deep result of Robertson and Seymour that for each xed k the problem can be solved in polynomial time in any undirected graph However for directed graphs the problem remains di cult even for k This was shown by Fortune Hopcroft and Wyllie
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