Difference between revisions of "Tree (graph theory)"

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A '''tree''' is an undirected [[Graph (graph theory)|graph]] which is both connected and acyclic. Equivalently, a tree is a graph <math>G=(V,E)</math> such that for any two vertices <math>u, v \in V</math> with <math>u \neq v</math>, there is exactly one path connecting <math>u</math> and <math>v</math> in <math>G</math>. Every tree on <math>|V|=n</math> vertices has exactly <math>n-1</math> edges.
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A '''tree''' is an undirected [[Graph (graph theory)|graph]] which is both connected and acyclic. Equivalently, a tree is a graph <math>G=(V,E)</math> such that for any two vertices <math>u, v \in V</math> with <math>u \neq v</math>, there is exactly one path connecting <math>u</math> and <math>v</math> in <math>G</math>. Every tree that has <math>|V|=n</math> vertices has exactly <math>n-1</math> edges.
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The converse is also true: an undirected and connected graph with <math>n</math> vertices and <math>n-1</math> edges is a tree.
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Revision as of 21:15, 4 July 2024

A tree is an undirected graph which is both connected and acyclic. Equivalently, a tree is a graph $G=(V,E)$ such that for any two vertices $u, v \in V$ with $u \neq v$, there is exactly one path connecting $u$ and $v$ in $G$. Every tree that has $|V|=n$ vertices has exactly $n-1$ edges.

The converse is also true: an undirected and connected graph with $n$ vertices and $n-1$ edges is a tree.

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