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  "body": "\n## Summary\n\nIn [[combinatorics|0JKW7W7XFR]] and order theory, a **multitree** may describe either of two equivalent structures: a directed acyclic graph (DAG) in which there is at most one directed path between any two vertices, or equivalently in which the subgraph reachable from any vertex induces an [[undirected tree|062D9KXJB1]], or a [[partially ordered set|0QV2JS9RJ3]] (poset) that does not have four items $a$, $b$, $c$, and $d$ forming a diamond suborder with $a \\le b \\le d$ and $a \\le c \\le d$ but with $b$ and $c$ incomparable to each other (also called a **diamond-free poset**).\n",
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