On sign-symmetric signed graphs

Ebrahim Ghorbani, Willem H. Haemers, Hamid Reza Maimani, Leila Parsaei Majd

Abstract


A signed graph is said to be sign-symmetric if it is switching isomorphic to its negation. Bipartite signed graphs are trivially sign-symmetric. We give new constructions of non-bipartite sign-symmetric signed graphs. Sign-symmetric signed graphs have a symmetric spectrum but not the other way around. We present constructions of signed graphs with symmetric spectra which are not sign-symmetric. This, in particular answers a problem posed by Belardo, Cioabă, Koolen, and Wang in 2018.


Keywords


Signed graph‎, ‎spectrum

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DOI: https://doi.org/10.26493/1855-3974.2161.f55

ISSN: 1855-3974

Issues from Vol 6, No 1 onward are partially supported by the Slovenian Research Agency from the Call for co-financing of scientific periodical publications