Discrete Mathematics Questions and Answers – Bipartite Graphs

This set of Discrete Mathematics Multiple Choice Questions & Answers (MCQs) focuses on “Bipartite Graphs”.

1. The maximum number of edges in a bipartite graph on 14 vertices is ___________
a) 56
b) 14
c) 49
d) 87
View Answer

Answer: c
Explanation: Maximum number of edges occur in a complete bipartite graph when every vertex has an edge to every opposite vertex in the graph. Number of edges in a complete bipartite graph is a*b, where a and b are no. of vertices on each side. This quantity is maximum when a = b i.e. when there are 7 vertices on each side. So answer is 7 * 7 = 49.

2. In a ______ the degree of each and every vertex is equal.
a) regular graph
b) point graph
c) star graph
d) euler graph
View Answer

Answer: c
Explanation: A regular graph has the same degree in each of its vertices. In a regular bipartite graph, if the common degree of each vertices is 1, the two parts are of the same size.

3. The time complexity to test whether a graph is bipartite or not is said to be _______ using depth first search.
a) O(n3)
b) linear time
c) O(1)
d) O(nlogn)
View Answer

Answer: b
Explanation: It is possible to test whether a graph is bipartite, and to return either a two-coloring (if it is bipartite) or an odd cycle (if it is not) in linear time i.e, O(n) using depth first search. In case of the intersection of n line segments or other simple shapes in the Euclidean graph, it is possible to test whether the graph is bipartite and it will return either a two-coloring or an odd cycle in time O(nlogn), even though the graph itself has up to O(n2) edges.
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4. The partition V = V1 ∪ V2 in a bipartite graph G1 is called ________
a) bipartition of G1
b) 2-vertex set of G1
c) sub bipartite graphs
d) disjoint vertex set
View Answer

Answer: b
Explanation: A graph G1(V, E) is called bipartite if its vertex set V(G) can be decomposed into two non-empty disjoint subsets V1(G1) and V2(G1) in such a way that each edge e ∈ E(G) has its one end joint in V1(G1) and other endpoint in V2(G1). The partition V = V1 ∪ V2 in a bipartite graph G1 is called bipartition of G1.

5. What is the maximum number of edges in a bipartite graph on 14 vertices?
a) 78
b) 15
c) 214
d) 49
View Answer

Answer: d
Explanation: By definition, the maximum possible number of edges in a bipartite graph on ‘n’ vertices = (1/4) x n2.
Substituting n = 14, we get maximum number of edges in a bipartite graph on 14 vertices,= (1/4) x (14)2
= (1/4) x 14 x 14
= 49
∴ Maximum number of edges in a bipartite graph on 14 vertices = 49.

6. In a complete bipartite graph, the intersection of two sub graphs is ______
a) 1
b) null
c) 210
d) 412
View Answer

Answer: b
Explanation: In a complete Bipartite graph, there must exist a partition say, V(G)=X∪Y and X∩Y=∅, that means all edges share a vertex from both set X and Y.

7. Bipartite graphs are used in ________
a) modern coding theory
b) colouring graphs
c) neural networks
d) chemical bonds
View Answer

Answer: a
Explanation: All types of cyclic graphs are examples of cyclic graphs. A cyclic graph is considered bipartite if all the cycles involved are of even length. Bipartite graphs are widely used in modern coding theory apart from being used in modeling relationships.
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8. All closed walks are of ______ length in a bipartite graph.
a) infinite
b) even
c) odd
d) odd prime
View Answer

Answer: b
Explanation: In a bipartite graph G all closed walks must be of even length as well as all cycles in G are of even length. Then only the graph is considered a bipartite graph.

9. Every complete bipartite graph must not be _______
a) planar graph
b) line graph
c) complete graph
d) subgraph
View Answer

Answer: c
Explanation: The below bipartite graph is not a complete graph as there is no edge between A-B, B-C, C-D, C-Q, P-Q, Q-R, Q-D and so it is not a complete graph.
The bipartite graph is not complete graph with no edge between A-B, B-C, C-D, C-Q, P-Q
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10. The spectrum of a graph is _______ if and only if it is _______ graph.
a) symmetry, bipartite
b) transitive, bipartite
c) cyclic, Euler
d) reflexive, planar
View Answer

Answer: a
Explanation: A graph is bipartite if and only if it does not contain an odd cycle. The spectrum of a graph is symmetric if and only if it is a bipartite graph. These are the characteristics of the graph.

Sanfoundry Global Education & Learning Series – Discrete Mathematics.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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