Quoting from Dasgupta, Papadimitrou, and Vazirani textbook:

“Trees A tree is an

p.135undirectedgraph that isconnectedandacyclic.”

Trees have these properties, quoting from DPV again:

- A tree on
**n nodes has n − 1 edge**s - Any
**connected, undirected**graph G = (V, E) with**|E| = |V| − 1 is a tree**. - An
**undirected**graph is a tree if and only if there is a**unique path between any pair of nodes**.