,b) be edge in G. The a illed endvertices of edges 页()音点 C acent in G; the vertex a is cn8 edge(a, b), and the vertex vertex of this edge. The g cident with the vertices a s called loop The vertex rtex if a vertex is not adjacent to any vertex g is an isolated vertex,(c, c), f are loop. a and b are adjacent; c and d are adjacent
❖ Definition 2：Let (a,b) be edge in G. The vertices a and b are called endvertices of edges; a and b are called adjacent in G; the vertex a is called initial vertex of edge (a,b), and the vertex b is called terminal vertex of this edge. The edge (a,b) is called incident with the vertices a and b. The edge (a,a) is called loop。The vertex is called isolated vertex if a vertex is not adjacent to any vertex. g is an isolated vertex, (c,c) ,(f,f) are loop. a and b are adjacent; c and d are adjacent;
1 not empty set. An undirected air of sets(V,E) such that E multiset of unordered pairs y G(V,E)the graph. The .v6 called vertices or simply called the set of vertices E are called " edge", and E 3 v4 es V={v1,V2V3,V4v52V6},E={V1,2},{v1,v5},{v2,V2 25V3j9V294 25V59 55{3V45V495jj edges v1v2, incidents with the vertices Vi and v2 loop isolated vertex edge (v2,v5) multiple edge
❖ Definition 3: Let V is not empty set. An undirected graph is an ordered pair of sets (V,E) such that E is a sub-multiset of the multiset of unordered pairs of V. We denote by G(V,E) the graph. The elements of V are called vertices or simply "points", and V is called the set of vertices. Similarly, elements of E are called "edge", and E is called the set of edges. V={v1 ,v2 ,v3 ,v4 ,v5 ,v6 }，E={{v1 ,v2 },{v1 ,v5 ,}，{v2 ,v2 }, {v2 ,v3 },{v2 ,v4 },{v2 ,v5 },{v2 ,v5 },{v3 ,v4 },{v4 ,v5 }}， edges {v1 ,v2 } incidents with the vertices v1 and v2 loop ; isolated vertex edge {v2 ,v5 } multiple edge