In this paper we consider the problem of finding the densest subset subject to co-matroid constraints. We are given a monotone supermodular set function f defined over a universe U, and the density of a subset S is defined to be f(S)/|S|. This generalizes the concept of graph density. Co-matroid constraints are the following: given matroid M a set S is feasible, iff the complement of S is independent in the matroid. Under such constraints, the problem becomes NP-hard. The specific case of graph density has been considered in literature under specific co-matroid constraints, for example, the cardinality matroid and the partition matroid. We show a 2-approximation for finding the densest subset subject to co-matroid constraints. Thereby we improve the approximation guarantees for the result for partition matroids in the literature.
Density Functions subject to a Co-Matroid Constraint
Venkatesan T. Chakaravarthy,Natwar Modani,Sivaramakrishnan R. Natarajan,Sambuddha Roy,Yogish Sabharwal
Published 2012 in Foundations of Software Technology and Theoretical Computer Science
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- Publication year
2012
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Foundations of Software Technology and Theoretical Computer Science
- Publication date
2012-07-22
- Fields of study
Mathematics, Computer Science
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