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  "body": "\n## Summary\n\nIn graph theory, an area of mathematics, **common graphs** belong to a branch of extremal graph theory concerning inequalities in homomorphism densities. Roughly speaking, $F$ is a common [[graph|00C0BR7D7H]] if it \"commonly\" appears as a subgraph, in a sense that the total number of copies of $F$ in any graph $G$ and its [[complement|0MCYJ72VGA]] $\\overline{G}$ is a large fraction of all possible copies of $F$ on the same vertices. Intuitively, if $G$ contains few copies of $F$, then its complement $\\overline{G}$ must contain lots of copies of $F$ in order to compensate for it.\n",
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