A1 Refereed original research article in a scientific journal
An improved lower bound for (1,≤2)-identifying codes in the king grid
Authors: Foucaud F, Laihonen T, Parreau A
Publisher: AMER INST MATHEMATICAL SCIENCES
Publication year: 2014
Journal: Advances in Mathematics of Communications
Journal name in source: ADVANCES IN MATHEMATICS OF COMMUNICATIONS
Journal acronym: ADV MATH COMMUN
Volume: 8
Issue: 1
First page : 35
Last page: 52
Number of pages: 18
ISSN: 1930-5346
DOI: https://doi.org/10.3934/amc.2014.8.35
We call a subset C of vertices of a graph G a (1, <= l)-identifying code if for all subset X of vertices with size at most l, the sets {c is an element of C vertical bar there exists u is an element of X, d(u, c) <= 1} are distinct. The concept of identifying codes was in in 1998 by Karpovsky, Chakrabarty and Levitin. Identifying codes have been studied in various grids. In particular, it has been shown that, there exists a (1, <= 2)-identifying code in the king grid with density (3)(7) and that there are no such identifying codes with density smaller than 5/12. Using a suitable frame and a discharging procedure, we improve the lower bound by showing that any (1, <= 2)-identifying code of the king grid has density at least 47/111. This reduces the gap between the best known lower and upper bounds on this problem by more than 56%.