English

Maximum list $r$-colorable induced subgraphs in $kP_3$-free graphs

Combinatorics 2025-05-05 v1 Discrete Mathematics Data Structures and Algorithms

Abstract

We show that, for every fixed positive integers rr and kk, \textsc{Max-Weight List rr-Colorable Induced Subgraph} admits a polynomial-time algorithm on kP3kP_3-free graphs. This problem is a common generalization of \textsc{Max-Weight Independent Set}, \textsc{Odd Cycle Transversal} and \textsc{List rr-Coloring}, among others. Our result has several consequences. First, it implies that, for every fixed r5r \geq 5, assuming PNP\mathsf{P}\neq \mathsf{NP}, \textsc{Max-Weight List rr-Colorable Induced Subgraph} is polynomial-time solvable on HH-free graphs if and only if HH is an induced subgraph of either kP3kP_3 or P5+kP1P_5+kP_1, for some k1k \geq 1. Second, it makes considerable progress toward a complexity dichotomy for \textsc{Odd Cycle Transversal} on HH-free graphs, allowing to answer a question of Agrawal, Lima, Lokshtanov, Rz{\k{a}}{\.z}ewski, Saurabh, and Sharma [TALG 2024]. Third, it gives a short and self-contained proof of the known result of Chudnovsky, Hajebi, and Spirkl [Combinatorica 2024] that \textsc{List rr-Coloring} on kP3kP_3-free graphs is polynomial-time solvable for every fixed rr and kk. We also consider two natural distance-dd generalizations of \textsc{Max-Weight Independent Set} and \textsc{List rr-Coloring} and provide polynomial-time algorithms on kP3kP_3-free graphs for every fixed integers rr, kk, and d6d \geq 6.

Keywords

Cite

@article{arxiv.2505.00412,
  title  = {Maximum list $r$-colorable induced subgraphs in $kP_3$-free graphs},
  author = {Esther Galby and Paloma T. Lima and Andrea Munaro and Amir Nikabadi},
  journal= {arXiv preprint arXiv:2505.00412},
  year   = {2025}
}