File:Tree_graph.svg · Wikimedia Commons · See Wikimedia Commons
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- Vertices
- v
- Edges
- v − 1
- Chromatic number
- 2 if v > 1
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In graph theory, a tree is an undirected graph in which every pair of distinct vertices is connected by exactly one path, or equivalently, a connected acyclic undirected graph. A forest is an undirected graph in which any two vertices are connected by at most one path, or equivalently an acyclic undirected graph, or equivalently a disjoint union of trees.
A directed tree, oriented tree, polytree, or singly connected network is a directed acyclic graph (DAG) whose underlying undirected graph is a tree. A polyforest (or directed forest or oriented forest) is a directed acyclic graph whose underlying undirected graph is a forest.
Connections
tree
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glossary of graph theory terms
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graph
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On-Line Encyclopedia of Integer Sequences
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spanning tree
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star graph
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graph connectivity measure
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computer science
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International Standard Book Number
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Wayback Machine
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digital object identifier
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International Standard Serial Number
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Gustav Kirchhoff
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Donald Knuth
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graph theory
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data structure
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statistical mechanics
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JSTOR
Organization
Q118398
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Arthur Cayley
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