Core Concepts
The paper introduces a new problem called open-separating dominating codes (OSD-codes) in graphs, which combines domination and open-separation properties. It studies the fundamental properties of OSD-codes, including their existence, hardness, and minimality, and compares them with another well-studied code called open locating-dominating codes (OLD-codes).
Abstract
The paper introduces a new problem called open-separating dominating codes (OSD-codes) in graphs, which combines the properties of domination and open-separation. The key highlights and insights are:
Existence of OSD-codes: A graph is OSD-admissible if and only if it has no open twins. Isolated vertices are allowed, but at most one.
Bounds on OSD-numbers: The OSD-number of a graph on n vertices without open twins is bounded between log n and n-1. The OSD-number is also bounded in relation to the LD-number and the OLD-number of the graph.
Hardness of the OSD-problem: The problem of determining the minimum OSD-code of a graph is NP-complete. Moreover, the problem of deciding whether the OSD-number and the OLD-number of a graph differ is also NP-complete.
Comparison of OSD-numbers and OLD-numbers: The paper analyzes the OSD-numbers and the OLD-numbers of various graph families, such as cliques, bipartite graphs (including half-graphs and double-stars), and split graphs (including headless spiders and thin suns). It shows that the two numbers can be equal or differ by at most one, depending on the graph family.
Polyhedra associated with OSD-codes: The paper provides an equivalent reformulation of the OSD-problem as a covering problem in a suitable hypergraph and discusses the polyhedra associated with OSD-codes, again in relation to OLD-codes of some graph families.