Loop (graph theory) (source code)

= Loop
{disambiguate=graph theory}
{wiki}

= Self-loop
{synonym}

= Graph loop
{synonym}

A self-loop is an <edge> whose two endpoints are the same <vertex>. In undirected total-degree counting it contributes two to the <degree of a vertex>, since both endpoints are incident to that <vertex>. Simple <graphs> exclude self-loops; the <linearized chord diagram model> retains them and starts from one self-loop.