Determining finite connected graphs along the quadratic embedding constants of paths

The QE constant of a finite connected graph G, denoted by QEC(G), is by definition the maximum of the quadratic function associated to the distance matrix on a certain sphere of codimension two. We prove that the QE constants of paths Pn form a strictly increasing sequence converging to −1/2. Then w...

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Main Authors: Baskoro, Edy Tri; Combinatorial Mathematics Research Group Faculty of Mathematics and Natural Sciences Institut Teknologi Bandung Indonesia (Author), Obata, Nobuaki; Graduate School of Information Sciences Tohoku University Send (Author)
Other Authors: JSPS Open Partnership Joint Research Project (Contributor)
Format: EJournal Article
Published: GTA Research Group, Univ. Newcastle, Indonesian Combinatorics Society and ITB, 2021-10-16.
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Summary:The QE constant of a finite connected graph G, denoted by QEC(G), is by definition the maximum of the quadratic function associated to the distance matrix on a certain sphere of codimension two. We prove that the QE constants of paths Pn form a strictly increasing sequence converging to −1/2. Then we formulate the problem of determining all the graphs G satisfying QEC(Pn)≤QEC(G)<QEC(Pn + 1). The answer is given for n = 2 and n = 3 by exploiting forbidden subgraphs for QEC(G)< − 1/2 and the explicit QE constants of star products of the complete graphs.
Item Description:https://www.ejgta.org/index.php/ejgta/article/view/1401