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  "body": "\n## Definition\n\nA tree is a [[graph|0JD5C82QMB]] that is [[connected|0FFAYNMAJZ]] and [[acyclic|0XNN9Z8E5A]].\n\n## Remarks\n\nLet $T$ be a finite graph with $n \\ge 1$ vertices. Then these conditions are equivalent: $T$ is a tree; $T$ is connected with $n - 1$ edges; $T$ is acyclic with $n - 1$ edges.\nA graph is a tree if and only if any two vertices are joined by exactly one path. The node [[unique paths in trees|096B7Q5742]] states this.\nThe [[path graphs|075WR6W3Y3]] and the stars $K_{1,n}$ are trees.\n\n## Explanations\n\n### L1 human\n\nA tree is a connected graph with no loops.\nA family tree and the folders on a computer are pictures of trees.\n",
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