Finite graph

A graph with finitely many vertices (and edges).
Finite graph

A G=(V,E)G=(V,E) is finite if its vertex set VV is finite. For a simple graph, this implies EE is finite as well.

If V=n|V|=n and E=m|E|=m, then for a simple undirected graph,

0m(n2). 0 \le m \le \binom{n}{2}.

Handshaking identity (useful fact). For a finite simple undirected graph,

vVdeg(v)=2E. \sum_{v\in V}\deg(v)=2|E|.

Finite graphs are the basic setting for many combinatorial arguments and algorithms, and they often arise as finite subgraphs of infinite graphs (for example, finite regions of the lattice ).