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Notes on Equitable Partitions into Matching Forests in Mixed Graphs and b-branchings in Digraphs

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Combinatorial Optimization (ISCO 2020)

Part of the book series: Lecture Notes in Computer Science ((LNTCS,volume 12176))

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Abstract

An equitable partition into branchings in a digraph is a partition of the arc set into branchings such that the sizes of any two branchings differ at most by one. For a digraph whose arc set can be partitioned into k branchings, there always exists an equitable partition into k branchings. In this paper, we present two extensions of equitable partitions into branchings in digraphs: those into matching forests in mixed graphs; and into b-branchings in digraphs. For matching forests, Király and Yokoi (2018) considered a tricriteria equitability based on the sizes of the matching forest, and the matching and branching therein. In contrast to this, we introduce a single-criterion equitability based on the number of the covered vertices. For b-branchings, we define an equitability based on the size of the b-branching and the indegrees of all vertices. For both matching forests and b-branchings, we prove that equitable partitions always exist.

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Notes

  1. 1.

    We believe that this notation causes no confusion on the direction of the arcs, since we never refer to the set of the tails of the arcs in this paper.

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Acknowledgements

This work is partially supported by JSPS KAKENHI Grant Numbers JP16K16012, JP20K11699, Japan.

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Correspondence to Kenjiro Takazawa .

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Takazawa, K. (2020). Notes on Equitable Partitions into Matching Forests in Mixed Graphs and b-branchings in Digraphs. In: Baïou, M., Gendron, B., Günlük, O., Mahjoub, A.R. (eds) Combinatorial Optimization. ISCO 2020. Lecture Notes in Computer Science(), vol 12176. Springer, Cham. https://doi.org/10.1007/978-3-030-53262-8_18

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  • DOI: https://doi.org/10.1007/978-3-030-53262-8_18

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