Lower bounds for the algebraic connectivity of graphs with specified subgraphs

The second smallest eigenvalue of the Laplacian matrix of a graph G is called the algebraic connectivity and denoted by a(G). We prove thata(G)>π2/3(p(12g(n1, n2, ..., np)2 − π2)/4g(n1, n2, ..., np)4 + 4(q − p)(3g(np + 1, np + 2, ..., nq)2 − π2)/g(np + 1, np + 2, ..., nq)4),holds for every non-tr...

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Main Author: Stanic, Zoran; Faculty of Mathematics, University of Belgrade, Studentski trg 16, 11 000 Belgrade, Serbia (Author)
Format: EJournal Article
Published: GTA Research Group, Univ. Newcastle, Indonesian Combinatorics Society and ITB, 2021-10-16.
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LEADER 02390 am a22002533u 4500
001 EJGTA_995_pdf_177
042 |a dc 
100 1 0 |a Stanic, Zoran; Faculty of Mathematics, University of Belgrade, Studentski trg 16, 11 000 Belgrade, Serbia  |e author 
100 1 0 |e contributor 
245 0 0 |a Lower bounds for the algebraic connectivity of graphs with specified subgraphs 
260 |b GTA Research Group, Univ. Newcastle, Indonesian Combinatorics Society and ITB,   |c 2021-10-16. 
500 |a https://www.ejgta.org/index.php/ejgta/article/view/995 
520 |a The second smallest eigenvalue of the Laplacian matrix of a graph G is called the algebraic connectivity and denoted by a(G). We prove thata(G)>π2/3(p(12g(n1, n2, ..., np)2 − π2)/4g(n1, n2, ..., np)4 + 4(q − p)(3g(np + 1, np + 2, ..., nq)2 − π2)/g(np + 1, np + 2, ..., nq)4),holds for every non-trivial graph G which contains edge-disjoint spanning subgraphs G1, G2, ...,  Gq such that, for 1 ≤ i ≤ p, a(Gi)≥a(Pni), with ni ≥ 2, and, for p + 1 ≤ i ≤ q, a(Gi)≥a(Cni), where Pni and Cni denote the path and the cycle of the corresponding order, respectively, and g denotes the geometric mean of given arguments. Among certain consequences, we emphasize the following lower bounda(G)>π212(4q − 3p)n2 − (16q − 15p)π2/12n4,referring to G which has n (n ≥ 2) vertices and contains p Hamiltonian paths and q − p Hamiltonian cycles, such that all of them are edge-disjoint. We also discuss the quality of the obtained lower bounds. 
540 |a Copyright (c) 2021 Electronic Journal of Graph Theory and Applications (EJGTA) 
546 |a eng 
690 |a edge-disjoint subgraphs, Laplacian matrix, algebraic connectivity, geometric mean, Hamiltonian cycle 
690 |a 05C50 
655 7 |a info:eu-repo/semantics/article  |2 local 
655 7 |a info:eu-repo/semantics/publishedVersion  |2 local 
655 7 |a Peer-reviewed Article  |2 local 
786 0 |n Electronic Journal of Graph Theory and Applications (EJGTA); Vol 9, No 2 (2021): Electronic Journal of Graph Theory and Applications; 257 - 263 
786 0 |n 2338-2287 
787 0 |n https://www.ejgta.org/index.php/ejgta/article/view/995/pdf_177 
856 4 1 |u https://www.ejgta.org/index.php/ejgta/article/view/995/pdf_177  |z Get Fulltext