An arborescence in a digraph is an acyclic arc subset in which every vertex except a root has exactly one incoming arc. In this paper, we show the reconfigurability of the union of k arborescences for fixed k in the following sense: for any pair of arc subsets that can be partitioned into k arborescences, one can be transformed into the other by exchanging arcs one by one so that every intermediate arc subset can also be partitioned into k arborescences. This generalizes the result by Ito et al. (2023), who showed the case with k = 1. Since the union of k arborescences can be represented as a common matroid basis of two matroids, our result gives a new non-trivial example of matroid pairs for which two common bases are always reconfigurable to each other.
@InProceedings{kobayashi_et_al:LIPIcs.ISAAC.2023.48, author = {Kobayashi, Yusuke and Mahara, Ryoga and Schwarcz, Tam\'{a}s}, title = {{Reconfiguration of the Union of Arborescences}}, booktitle = {34th International Symposium on Algorithms and Computation (ISAAC 2023)}, pages = {48:1--48:14}, series = {Leibniz International Proceedings in Informatics (LIPIcs)}, ISBN = {978-3-95977-289-1}, ISSN = {1868-8969}, year = {2023}, volume = {283}, editor = {Iwata, Satoru and Kakimura, Naonori}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ISAAC.2023.48}, URN = {urn:nbn:de:0030-drops-193502}, doi = {10.4230/LIPIcs.ISAAC.2023.48}, annote = {Keywords: Arborescence packing, common matroid basis, combinatorial reconfiguration} }
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