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:

    “Kittering’s brain. What we will he think when he resumes life in that body? Will he thank us for giving him a new lease on life? Or will he object to finding his ego living in that human junk heap?”
    —W. Scott Darling, and Erle C. Kenton. Dr. Frankenstein (Sir Cedric Hardwicke)

    “I have defeated them all.... I was left with some money to battle with the world when quite young, and at the present time have much to feel proud of.... The Lord gave me talent, and I know I have done good with it.... For my brains have made me quite independent and without the help of any man.”
    —Harriet A. Brown, U.S. inventor and educator. As quoted in Feminine Ingenuity, ch. 8, by Anne L. MacDonald (1992)

    “This is certainly not the place for a discourse about what festivals are for. Discussions on this theme were plentiful during that phase of preparation and on the whole were fruitless. My experience is that discussion is fruitless. What sets forth and demonstrates is the sight of events in action, is living through these events and understanding them.”
    —Doris Lessing (b. 1919)