• graphs;
  • cycles;
  • extremal graphs;
  • minimal saturated graphs


A graph G is called H-saturated if it does not contain any copy of H, but for any edge e in the complement of G, the graph inline image contains some H. The minimum size of an n-vertex H-saturated graph is denoted by inline image. We prove

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holds for all inline image, where inline image is a cycle with length k. A graph G is H-semisaturated if inline image contains more copies of H than G does for inline image. Let inline image be the minimum size of an n-vertex H-semisaturated graph. We have

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We conjecture that our constructions are optimal for inline image. © 2012 Wiley Periodicals, Inc. J. Graph Theory 73: 203–215, 2013