posted on 2024-07-25, 12:38authored byFlorian HörschFlorian Hörsch, András Imolay, Ryuhei Mizutani, Taihei Oki, Tamás Schwarcz
Consider a matroid equipped with a labeling of its ground set to an abelian group. We define the label of a subset of the ground set as the sum of the labels of its elements. We study a collection of problems on finding bases and common bases of matroids with restrictions on their labels. For zero bases and zero common bases, the results are mostly negative. While finding a non-zero basis of a matroid is not difficult, it turns out that the complexity of finding a non-zero common basis depends on the group. Namely, we show that the problem is hard for a fixed group if it contains an element of order two, otherwise it is polynomially solvable. As a generalization of both zero and non-zero constraints, we further study F-avoiding constraints where we seek a basis or common basis whose label is not in a given set F of forbidden labels. Using algebraic techniques, we give a randomized algorithm for finding an F-avoiding common basis of two matroids represented over the same field for finite groups given as operation tables. The study of F-avoiding bases with groups given as oracles leads to a conjecture stating that whenever an F-avoiding basis exists, an F-avoiding basis can be obtained from an arbitrary basis by exchanging at most |F| elements. We prove the conjecture for the special cases when |F| ≤ 2 or the group is ordered. By relying on structural observations on matroids representable over fixed, finite fields, we verify a relaxed version of the conjecture for these matroids. As a consequence, we obtain a polynomial-time algorithm in these special cases for finding an F-avoiding basis when |F| is fixed.
History
Editor
Bringmann K ; Grohe M ; Puppis G ; Svensson O
Primary Research Area
Algorithmic Foundations and Cryptography
Name of Conference
International Colloquium on Automata Languages and Programming (ICALP)
Journal
51st International Colloquium on Automata, Languages, and Programming (ICALP 2024)
Volume
297
Page Range
86:1-86:20
Publisher
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
BibTeX
@inproceedings{Hörsch:Imolay:Mizutani:Oki:Schwarcz:2024,
title = "Problems on Group-Labeled Matroid Bases",
author = "Hörsch, Florian" AND "Imolay, András" AND "Mizutani, Ryuhei" AND "Oki, Taihei" AND "Schwarcz, Tamás",
editor = "Bringmann, Karl" AND "Grohe, Martin" AND "Puppis, Gabriele" AND "Svensson, Ola",
year = 2024,
month = 7,
journal = "51st International Colloquium on Automata, Languages, and Programming (ICALP 2024)",
pages = "86:1--86:20",
publisher = "Schloss Dagstuhl – Leibniz-Zentrum für Informatik",
issn = "1868-8969",
doi = "10.4230/LIPIcs.ICALP.2024.86"
}