Graph Terminology II

Cycles

A cycle is similar to a path, except that its first and last nodes are identical. In other words, a cycle is like a path that loops back into itself.

The following example graph shows the cycle $a \to c \to d \to a$ marked in blue.

In an undirected graph, a single edge between nodes $u$ and $v$ consists of the two “half-edges” $(u, v)$ and $(v, u)$. However, the walk $u \to v \to u$ ...