episciences.org_6108_1635086562 1635086562 episciences.org raphael.tournoy+crossrefapi@ccsd.cnrs.fr episciences.org Discrete Mathematics & Theoretical Computer Science 1365-8050 06 08 2021 vol. 23 no. 1 Graph Theory Destroying Bicolored $P_3$s by Deleting Few Edges Niels Grüttemeier Christian Komusiewicz Jannik Schestag Frank Sommer We introduce and study the Bicolored $P_3$ Deletion problem defined as follows. The input is a graph $G=(V,E)$ where the edge set $E$ is partitioned into a set $E_r$ of red edges and a set $E_b$ of blue edges. The question is whether we can delete at most $k$ edges such that $G$ does not contain a bicolored $P_3$ as an induced subgraph. Here, a bicolored $P_3$ is a path on three vertices with one blue and one red edge. We show that Bicolored $P_3$ Deletion is NP-hard and cannot be solved in $2^{o(|V|+|E|)}$ time on bounded-degree graphs if the ETH is true. Then, we show that Bicolored $P_3$ Deletion is polynomial-time solvable when $G$ does not contain a bicolored $K_3$, that is, a triangle with edges of both colors. Moreover, we provide a polynomial-time algorithm for the case that $G$ contains no blue $P_3$, red $P_3$, blue $K_3$, and red $K_3$. Finally, we show that Bicolored $P_3$ Deletion can be solved in $O(1.84^k\cdot |V| \cdot |E|)$ time and that it admits a kernel with $O(k\Delta\min(k,\Delta))$ vertices, where $\Delta$ is the maximum degree of $G$. 06 08 2021 6108 arXiv:1901.03627 10.46298/dmtcs.6108 https://dmtcs.episciences.org/6108