2. Definition of graph:
Graphs are discrete structures consisting of vertices and edges
that connect these vertices. There are different kinds of
graphs, depending on whether edges have directions, whether
multiple edges can connect the same pair of vertices, and
whether loops are allowed, whether weight of edges are
given, etc.
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3. Types of graph
1. Finite graph: A finite graph is a graph in which the vertex set
and the edge set are finite sets.
2. Infinite graph: A infinite graph is a graph in which the vertex
set and the edge set are infinite sets.
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4. 3. Undirected graph: An undirected graph is a graph in which
edges have no orientation.
4. Directed graph: A directed graph is a graph in which edges
have orientations.
5. Mixed graph: A mixed graph is a graph in which some edges
may be directed and some may be undirected.
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5. 6. Simple graph: A simple graph is an undirected graph
without multiple edges or loops.
7. Multigraph: Multiple edges are two or more edges that
connect the same two vertices. A loop is an edge that
connects a vertex to itself.
8. Psuedograph :A graph in which loops and multiple edges
are allowed is called psuedograph.
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6. 9. Complete Graph- A simple graph G is said to be complete
if every vertex in G is connected with every other vertex.
10. Regular Graph- A graph in which all the vertices are of
equal degree is called a regular graph.
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7. 11. Cubic graph: Cubic graph is a graph in which all vertices
have degree three. In other words, a cubic graph is a 3-
regular graph.
12.Cyclic Graph: A graph with continuous sequence of vertices
and edges is called a cyclic graph.
13. Wheel graph: A wheel graph is a graph formed by
connecting a single universal vertex to all vertices of a cycle.
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8. 14. Weighted graph: A weighted graph is a graph in which a
number (the weight) is assigned to each edge.
15. Bipartite graph: A bipartite graph is a graph in which the
vertex set can be partitioned into two sets.
16. Complete Bipartite Graph: A complete bipartite graph is a
bipartite graph in which each vertex in the first set is joined to
every single vertex in the second set.
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