We prove several tight bounds on the chromatic number of a graph in terms of the minimum number of simple cycles covering a vertex or an edge of this graph. Namely, we prove that X(G) ≤ k in the following two cases: any edge of G is covered by less than [e(k − 1) ! − 1] simple cycles, or any vertex of G is covered by less than \( \left[\frac{ek!}{2}-\frac{k+1}{2}\right] \) simple cycles. Tight bounds on the number of simple cycles covering an edge or a vertex of a k-critical graph are also proved.
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Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 450, 2016, pp. 5–13.
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Berlov, S.L., Tyschuk, K.I. On the Connection Between the Chromatic Number of a Graph and the Number of Cycles Covering a Vertex or an Edge. J Math Sci 232, 1–5 (2018). https://doi.org/10.1007/s10958-018-3853-6
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DOI: https://doi.org/10.1007/s10958-018-3853-6