Independent Set (graph Theory) - Finding Independent Sets

Finding Independent Sets

Further information: Clique problem

In computer science, several computational problems related to independent sets have been studied.

  • In the maximum independent set problem, the input is an undirected graph, and the output is a maximum independent set in the graph. If there are multiple maximum independent sets, only one need be output.
  • In the maximum-weight independent set problem, the input is an undirected graph with weights on its vertices and the output is an independent set with maximum total weight. The maximum independent set problem is the special case in which all weights are one.
  • In the maximal independent set listing problem, the input is an undirected graph, and the output is a list of all its maximal independent sets. The maximum independent set problem may be solved using as a subroutine an algorithm for the maximal independent set listing problem, because the maximum independent set must be included among all the maximal independent sets.
  • In the independent set decision problem, the input is an undirected graph and a number k, and the output is a Boolean value: true if the graph contains an independent set of size k, and false otherwise.

The first three of these problems are all important in practical applications; the independent set decision problem is not, but is necessary in order to apply the theory of NP-completeness to problems related to independent sets.

The independent set problem and the clique problem are complementary: a clique in G is an independent set in the complement graph of G and vice versa. Therefore, many computational results may be applied equally well to either problem. For example, the results related to the clique problem have the following corollaries:

  • The decision problem is NP-complete, and hence it is not believed that there is an efficient algorithm for solving it.
  • The maximum independent set problem is NP-hard and it is also hard to approximate.

Read more about this topic:  Independent Set (graph Theory)

Famous quotes containing the words finding, independent and/or sets:

    We are paid for our suspicions by finding what we suspected.
    Henry David Thoreau (1817–1862)

    The ability to secure an independent livelihood and honorable employ suited to her education and capacities is the only true foundation of the social elevation of woman, even in the very highest classes of society. While she continues to be educated only to be somebody’s wife, and is left without any aim in life till that somebody either in love, or in pity, or in selfish regard at last grants her the opportunity, she can never be truly independent.
    Catherine E. Beecher (1800–1878)

    It is odd but agitation or contest of any kind gives a rebound to my spirits and sets me up for a time.
    George Gordon Noel Byron (1788–1824)