Our key definition is that of a two-eigenvalue cover, (or 2ev-cover) which is a covering graph whose adjacency spectra differs (as a multiset) from that of the graph it covers by exactly two eigenvalues.
Mar 2, 2020 · We develop a framework in which this connection is a natural first example of the relationship between group labeled adjacency matrices with few ...
Oct 7, 2020 · 2ev-covering graphs occur frequently in the study of distance-regular graphs, where this two eigenvalue condition is necessary for a lifted ...
In particular, we define a two-eigenvalue cover to be a covering graph whose adjacency spectra differs (as a multiset) from that of the graph it covers by ...
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Graph covers with two new eigenvalues · C. Godsil, M. Levit, Olha Silina · Published in European journal of… 2 March 2020 · Mathematics · Eur. J. Comb.
Aug 6, 2021 · There is no simple formula in general. The join of G and H is the complement of the disjoint union of the complements of G and H. So we are ...
Mar 4, 2018 · In each of these cases, the new eigenvalues are roots of pAG(x)2 or pAG(x2), respectively. Moreover, note that up to isomorphism in the 2-fold ...
Aug 24, 2016 · Given two graph G and H if they have the same characteristic polynomial and it does not have any repeated roots,then G and H are isomorphic ? if ...
Oct 17, 2023 · This is a limited partial answer to the question ruling out the case where the graph is regular and has four distinct eigenvalues, ...