Incidence (graph)

In graph theory, an incidence is a pair ${\displaystyle (u,e)}$ where ${\displaystyle u}$ is a vertex and ${\displaystyle e}$ is an edge incident to ${\displaystyle u}$.

Two distinct incidences ${\displaystyle (u,e)}$ and ${\displaystyle (v,f)}$ are adjacent if and only if ${\displaystyle u=v}$, ${\displaystyle e=f}$ or ${\displaystyle uv=e}$ or ${\displaystyle f}$.

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