منابع مشابه
Packing Non-Returning A-Paths
Chudnovsky et al. gave a min-max formula for the maximum number of node-disjoint non-zero A-paths in group-labeled graphs [1], which is a generalization of Mader’s theorem on node-disjoint A-paths [3]. Here we present a further generalization with a shorter proof. The main feature of Theorem 2.1 is that parity is “hidden” inside ν̂, which is given by an oracle for non-bipartite matching.
متن کاملPacking non-returning A-paths algorithmically
In this paper we present an algorithmic approach to packing A-paths. It is regarded as a generalization of Edmonds’ matching algorithm, however there is the significant difference that here we do not build up any kind of alternating tree. Instead we use the so-called 3-way lemma, which either provides augmentation, or a dual, or a subgraph which can be used for contraction. The method works in ...
متن کاملPacking Non-Zero A-Paths In Group-Labelled Graphs
Let G=(V,E) be an oriented graph whose edges are labelled by the elements of a group Γ and let A⊆V . An A-path is a path whose ends are both in A. The weight of a path P in G is the sum of the group values on forward oriented arcs minus the sum of the backward oriented arcs in P . (If Γ is not abelian, we sum the labels in their order along the path.) We are interested in the maximum number of ...
متن کاملPacking paths in digraphs
Let G be a xed collection of digraphs. Given a digraph H, a Gpacking of H is a collection of vertex disjoint subgraphs of H, each isomorphic to a member of G. A G-packing, P, is maximum if the number of vertices belonging to some member of P is maximum, over all G-packings. The analogous problem for undirected graphs has been extensively studied in the literature. We concentrate on the cases wh...
متن کاملLinear-Time FPT Algorithms via Half-Integral Non-returning A-path Packing
A recent trend in the design of FPT algorithms is exploiting the half-integrality of LP relaxations. In other words, starting with a half-integral optimal solution to an LP relaxation, we assign integral values to variables one-by-one by branch and bound. This technique is general and the resulting time complexity has a low dependency on the parameter. However, the time complexity often becomes...
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ژورنال
عنوان ژورنال: Combinatorica
سال: 2007
ISSN: 0209-9683,1439-6912
DOI: 10.1007/s00493-007-0056-z