Support of closed walks and second eigenvalue multiplicity of graphs
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- Support of closed
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We show that the multiplicity of the second normalized adjacency matrix eigenvalue of any connected graph of maximum degree ?is bounded by O(n ?7/5/log1/5-o(1)n) for any ?, and improve this to O(nlog1/2d/log1/4-o(1)n) for simple d-regular graphs when d? log1/4n. In fact, the same bounds hold for the number of eigenvalues in any interval of width ?2/log?1-o(1)n containing the second eigenvalue ?2. The main ingredient in the proof is a polynomial (in k) lower bound on the typical support of a closed random walk of length 2k in any connected graph, which in turn relies on new lower bounds for the entries of the Perron eigenvector of submatrices of the normalized adjacency matrix.
|Title of host publication||STOC 2021 - Proceedings of the 53rd Annual ACM SIGACT Symposium on Theory of Computing|
|Editors||Samir Khuller, Virginia Vassilevska Williams|
|Publisher||Association for Computing Machinery, Inc.|
|Publication status||Published - 2021|
|Event||53rd Annual ACM SIGACT Symposium on Theory of Computing, STOC 2021 - Virtual, Online, Italy|
Duration: 21 Jun 2021 → 25 Jun 2021
|Conference||53rd Annual ACM SIGACT Symposium on Theory of Computing, STOC 2021|
|Periode||21/06/2021 → 25/06/2021|
|Sponsor||ACM Special Interest Group on Algorithms and Computation Theory (SIGACT)|
© 2021 Owner/Author.
- eigenvalue multiplicity, normalized adjacency matrix, random walks in graphs