We investigate the 2-domination number for grid graphs, that is the size of a smallest set $D$ of vertices of the grid such that each vertex of the grid belongs to $D$ or has at least two neighbours in $D$. We give a closed formula giving the 2-domination number of any $n \!\times\! m$ grid, hereby confirming the results found by Lu and Xu, and Shaheen et al. for $n \leq 4$ and slightly correct the value of Shaheen et al. for $n = 5$. The proof relies on some dynamic programming algorithms, using transfer matrices in (min,+)-algebra. We also apply the method to solve the Roman domination problem on grid graphs.

Source : oai:arXiv.org:1810.12896

Volume: vol. 21 no. 1, ICGT 2018

Published on: May 23, 2019

Submitted on: November 2, 2018

Keywords: Computer Science - Discrete Mathematics,Mathematics - Combinatorics