Table of Contents

Incidence and Adjacency

let e_x be an edge joining two vertices Vi and V_j then e_x is said to be incident of V_iand V_{j .}

Two vertices are said to be adjacent if there exist an edge joining this vertices.

where e₁ is incident of V₁ and V₂ and V₁&V2 are adjacent but V₃ and V₄ are not adjacent.

Degree & Vertex

The degree of vertex V in a graph G written as d(V) is equal to number of edges which are incident on V with self loop counted twice.

Here, d(V₁)=2

d(V₂)=4

d(V₃)=2

d(V₄)=3

d(V₅)=2

d(V₆)=2

d(V₇)=1

d(V₈)=0

A vertex having o is called isolated vertex and a vertex having degree l is called pendant vertex.

A graph with a finite number of vertices as well as edge is called finite graph otherwise it is a infinite graph.