Describe G formally that is find the set V G of vertices of
     Describe G formally, that is, find the set V (G) of vertices of G and the set E(G) of edges of G. (b)Find the degree of each vertex and degree of graph.  2.Find the adjacency matrix A = [aij] if each graph G in FIg.2.  3. Draw all possible nonsimilar: (a) binary trees T with three nodes (circle); (b) 2-trees T\' with for external nodes (square). 
  
  Solution
a) Graphs: G = {V,E} A collection of vertices and edges.
Vertices/Vertex Set– V(G)
Point, vertex, etc. We give a letter/number name.
Example: V = {v1,v2} V = {A,B,C,D, E}
Edges/Edge Set – E(G)
A choice of two points to tie an edge between. This may be the same point, but it does not matter which order they are.
b) The graph G has deg(A) = 3, deg(B) = 3, deg(C) = 4, deg(D)=2 and deg(E) = 2.

