Definition:Tree (Graph Theory)

Also defined as
In some contexts, the term tree is used to mean rooted tree.

Also see

 * Equivalence of Definitions of Tree


 * All trees are bipartite, from Graph is Bipartite iff No Odd Cycles (as a tree has no cycles at all).


 * No (non-edgeless) tree is Eulerian, as it has no circuits, let alone Eulerian ones.