A graph \(G\) is called acyclic if it has no cycles, a tree is an acyclic connected graph
- every two vertices of a tree \(T\) are connected by a unique path
- every nontrivial tree has at least two end-vertices
- if \(T\) is a tree of order \(n\) then the size of the tree is \(m = n - 1\)
- additional definitions