A1 Refereed original research article in a scientific journal
Optimal lower bound for 2-identifying codes in the hexagonal grid
Authors: Junnila V, Laihonen T
Publisher: ELECTRONIC JOURNAL OF COMBINATORICS
Publication year: 2012
Journal: The Electronic Journal of Combinatorics
Journal name in source: ELECTRONIC JOURNAL OF COMBINATORICS
Journal acronym: ELECTRON J COMB
Number in series: 2
Volume: 19
Issue: 2
Number of pages: 16
ISSN: 1077-8926
Abstract
An r-identifying code in a graph G = (V, E) is a subset C subset of V such that for each u is an element of V the intersection of C and the ball of radius r centered at u is non-empty and unique. Previously, r-identifying codes have been studied in various grids. In particular, it has been shown that there exists a 2-identifying code in the hexagonal grid with density 4/19 and that there are no 2-identifying codes with density smaller than 2/11. Recently, the lower bound has been improved to 1/5 by Martin and Stanton (2010). In this paper, we prove that the 2-identifying code with density 4/19 is optimal, i.e. that there does not exist a 2-identifying code in the hexagonal grid with smaller density.
An r-identifying code in a graph G = (V, E) is a subset C subset of V such that for each u is an element of V the intersection of C and the ball of radius r centered at u is non-empty and unique. Previously, r-identifying codes have been studied in various grids. In particular, it has been shown that there exists a 2-identifying code in the hexagonal grid with density 4/19 and that there are no 2-identifying codes with density smaller than 2/11. Recently, the lower bound has been improved to 1/5 by Martin and Stanton (2010). In this paper, we prove that the 2-identifying code with density 4/19 is optimal, i.e. that there does not exist a 2-identifying code in the hexagonal grid with smaller density.
UTU Research Portal