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Neither Wikipedia nor mathworld gave the answer: What is the name of the edge (or multiple edges) without which a DAG would be a tree? Or maybe instead: What is the name of the subgraph such that there are two (or more) distinct directed paths from one node to another node?

Here's the context: I'm rewriting documentation that describes two different sets of rules for the edges of a graph: one set applies when you're talking about edges that form a tree, the other, that form a DAG but not a tree. The documentation currently refers to these as "acyclic edges" and "cyclic edges" but that isn't right ...

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These correspond to what would be cycles if you interpreted your DAG as an undirected graph. So possibly something related to the phrase undirected cycle? –  Rahul Jul 15 '14 at 3:40

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