A graph is an ordered pair V,E of sets V of vertices and E of edges, that are disjoint together with an incedence function ϕ:E→V×V that associates with
Degree of a Vertex
Suppose that G=(V,E) is a graph, then we say that the degree of a vertex v is the number of other vertices connected to it with an edge. We define the syntax deg:V→N0 to be the function that maps a node to it's degree.
Sum of Degrees
Suppose that G is a finite graph, then we have that
∑v∈Vdeg(v)=2|E|
Branching Factor
Suppose that we have a graph G, then we say that G has branching factorb∈N1, if every vertex has degreeb
Average Branching Factor
Suppose that G is a finite graph, then the average branching factor of the graph is defined as
∑v∈Vdeg(v)|V|∈Q
Maximum Branching Factor
Suppose that we have a graph G, then we say that G has a maximum branching factor ofb∈N0, if every vertex has degree at most b
Path
A tuple (v1,v2,…vn)∈Vn is said to be a path if for every i∈[1…n−1], {vi,vi+1}∈E.
Connected Vertices
Suppose that u,v∈V, then we say that u,v are connected if there is a path v1,v2,…,vn where v1=u and vn=v
Connected Graph
Given a graph G we say that it is connected when for every u,v∈V, we have that u and v are connected.
A Graph with One Vertex is Connected
Suppose that G=(V,E) where V={x}, then G is conntected.
Suppose that u,v∈V, then u=v=x, therefore the path x connects it to itself.
A Disconnected Graph is the Union of Many Disjoint Connected Subgraphs
Suppose that G is a disconnected graph, then G is the disjoint union of 2 or more connected subgraphs