Discrete Mathematics & Theoretical Computer Science |

- 1 Institut Fourier
- 2 Laboratoire Leibniz
- 3 Department of Mathematics [Uppsala]
- 4 Uppsala University
- 5 Coding Theory Research Group
- 6 Department of Physics and Astronomy [Turku]

Let $G=(V,E)$ be an undirected graph without loops and multiple edges. A subset $C\subseteq V$ is called \emph{identifying} if for every vertex $x\in V$ the intersection of $C$ and the closed neighbourhood of $x$ is nonempty, and these intersections are different for different vertices $x$. Let $k$ be a positive integer. We will consider graphs where \emph{every} $k$-subset is identifying. We prove that for every $k>1$ the maximal order of such a graph is at most $2k-2.$ Constructions attaining the maximal order are given for infinitely many values of $k.$ The corresponding problem of $k$-subsets identifying any at most $\ell$ vertices is considered as well.

Source: HAL:hal-00362184v1

Volume: Vol. 16 no. 1

Section: Combinatorics

Published on: March 1, 2014

Accepted on: July 23, 2015

Submitted on: February 16, 2010

Keywords: [MATH.MATH-CO] Mathematics [math]/Combinatorics [math.CO]

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