Abstract
For a graph G, let f(G) be the maximum number of edges in a cut of G. For a positive integer m and a set of graphs \(\mathscr {H}\), let \(f(m,\mathscr {H})\) be the minimum possible cardinality of f(G), as G ranges over all graphs on m edges which contain no graphs in \(\mathscr {H}\). Suppose that \(r\ge 8\) is an even integer and \(\mathscr {H}=\{C_{5},C_{6},\ldots ,C_{r-1}\}\). In this paper, we prove that \(f(m,\mathscr {H})\ge m/2+cm^{\frac{r}{r+1}}\) for some real \(c>0\), which improves a result of Alon et al. We also give a general lower bound on \(f(m,\mathscr {H})\) when \(\mathscr {H}=\{K_{s}+\overline{K_{t}}\}\). This extends a result of Zeng and Hou.
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Ma, H. Maximum Cuts in \(\mathscr {H}\)-Free Graphs. Graphs and Combinatorics 36, 1503–1516 (2020). https://doi.org/10.1007/s00373-020-02189-2
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DOI: https://doi.org/10.1007/s00373-020-02189-2