Negative closed walks in signed graphs: A note

10/14/2019

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by   Andrzej Szepietowski, et al.

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Recently Naserasr, Sopena, and Zaslavsky [R. Naserasr, É. Sopena, T. Zaslavsky,Homomorphisms of signed graphs: An update, arXiv: 1909.05982v1 [math.CO] 12 Sep 2019.] published a report on closed walks in signed graphs. They gave a characterization of the sets of closed walks in a graph G which corespond to the set of negative walks in some signed graph on G. In this note we show that their characterization is not valid and give a new characterization.