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  "body": "\n## Statement\n\nLet $m, n \\ge 1$ be integers.\nThen the [[chromatic number|0C5M7AM6FH]] of the [[complete bipartite graph|0V0GC7BQAN]] $K_{m,n}$ is $2$.\n\n## Remarks\n\nGive one colour to each of the two parts. Each edge joins the two parts, so this is a colouring with $2$ colours.\nOne colour is not enough, because $K_{m,n}$ has an edge.\nMore generally, a [[bipartite|07DVHJ8N0A]] graph with at least one edge has chromatic number $2$.\n\n## Explanations\n\n### L1 human\n\nColour one side of $K_{m,n}$ red and the other side blue.\nEvery edge goes from red to blue, so two colours are enough, and one colour is too few.\n",
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