Tail

In graph theory, the tail ^[1] of a directed edge $(u,v)$ is its first vertex $u$, the vertex from which the edge points away; the other endpoint, $v$, is called the edge’s head.

Definition

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Definition 1 (Tail)

Let $(u,v)$ be a directed edge. The vertex $u$ is called the tail of the edge.

References

1. [1]

   “Directed graph”, Wikipedia, Available: https://en.wikipedia.org/wiki/Directed_graph, Accessed: 2026-07-14 ↩