Ekinci, Gulnaz BoruzanliBujtas, Csilla2023-01-122023-01-1220221234-30992083-58921234-30992083-5892https://doi.org/10.7151/dmgt.2452https://hdl.handle.net/11454/79060The 2-domination number gamma(2)(G) of a graph G is the minimum cardinality of a set D subset of V (G) for which every vertex outside D is adjacent to at least two vertices in D. Clearly, gamma(2)(G) cannot be smaller than the domination number gamma(G). We consider a large class of graphs and characterize those members which satisfy gamma(2) = gamma. For the general case, we prove that it is NP-hard to decide whether gamma(2) = gamma holds. We also give a necessary and sufficient condition for a graph to satisfy the equality hereditarily.en10.7151/dmgt.2452info:eu-repo/semantics/openAccessdomination number2-domination numberhereditary propertycomputational complexityK-DominationAnnihilation NumberTransversal NumbersGraphsBoundsArticleWOS:0007717036000012-s2.0-85127857706Q3Q3