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  "body": "\n## Definition\n\nA multigraph is a triple $G = (V, E, r)$ of a set $V$ of vertices, a set $E$ of edges, and a map $r$.\nThe map $r$ assigns to each edge $e \\in E$ a set $r(e) \\subseteq V$ of one or two vertices, the ends of $e$.\nTwo distinct edges may have the same ends. Such edges are parallel, or multiple, edges.\nAn edge with only one end is a loop.\n\n## Remarks\n\nSome authors do not allow loops in a multigraph, and they call a multigraph with loops a pseudograph.\nA [[graph|0JD5C82QMB]] is a multigraph without loops and without parallel edges.\nThe [[Seven Bridges of Königsberg|0YCW781Q9D]] form a multigraph with $4$ vertices and $7$ edges.\n\n## Explanations\n\n### L1 human\n\nA multigraph is like a graph, but two points can be joined by several lines.\nA road map with two different roads between the same two towns is a multigraph.\n",
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  "name": "Multigraph",
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