Exponential independence in subcubic graphs

Autor: Johannes Pardey, Dieter Rautenbach, Stéphane Bessy
Přispěvatelé: Algorithmes, Graphes et Combinatoire (ALGCO), Laboratoire d'Informatique de Robotique et de Microélectronique de Montpellier (LIRMM), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM), Universität Ulm - Ulm University [Ulm, Allemagne]
Rok vydání: 2021
Předmět:
Zdroj: Discrete Mathematics
Discrete Mathematics, Elsevier, 2021, 344 (8), pp.#112439. ⟨10.1016/j.disc.2021.112439⟩
ISSN: 0012-365X
DOI: 10.1016/j.disc.2021.112439
Popis: A set S of vertices of a graph G is exponentially independent if, for every vertex u in S, ∑ v ∈ S ∖ { u } ( 1 2 ) dist ( G , S ) ( u , v ) − 1 1 , where dist ( G , S ) ( u , v ) is the distance between u and v in the graph G − ( S ∖ { u , v } ) . The exponential independence number α e ( G ) of G is the maximum order of an exponentially independent set in G. In the present paper we present several bounds on this parameter and highlight some of the many related open problems. In particular, we prove that subcubic graphs of order n have exponentially independent sets of order Ω ( n / log 2 ⁡ ( n ) ) , that the infinite cubic tree has no exponentially independent set of positive density, and that subcubic trees of order n have exponentially independent sets of order ( n + 3 ) / 4 .
Databáze: OpenAIRE