# Constant ratio fixed-parameter approximation of the edge multicut problem

Marx, D. and Razgon, Igor
(2009)
Constant ratio fixed-parameter approximation of the edge multicut problem.
In:
Fiat, A. and Sanders, P. (eds.)
*Algorithms.*
Berlin, Germany:
Springer Verlag, pp. 647-658.
ISBN 9783642041280.

## Abstract

The input of the Edge Multicut problem consists of an undirected graph G and pairs of terminals {s 1,t 1}, ..., {s m ,t m }; the task is to remove a minimum set of edges such that s i and t i are disconnected for every 1 ≤ i ≤ m. The parameterized complexity of the problem, parameterized by the maximum number k of edges that are allowed to be removed, is currently open. The main result of the paper is a parameterized 2-approximation algorithm: in time f(k)·n O(1), we can either find a solution of size 2k or correctly conclude that there is no solution of size k. The proposed algorithm is based on a transformation of the Edge Multicut problem into a variant of parameterized Max-2-SAT problem, where the parameter is related to the number of clauses that are not satisfied. It follows from previous results that the latter problem can be 2-approximated in a fixed-parameter time; on the other hand, we show here that it is W[1]-hard. Thus the additional contribution of the present paper is introducing the first natural W[1]-hard problem that is constant-ratio fixed-parameter approximable.

## Metadata

Item Type: | Book Section |
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School: | Birkbeck Schools and Departments > School of Business, Economics & Informatics > Computer Science and Information Systems |

Depositing User: | Sarah Hall |

Date Deposited: | 01 Aug 2013 15:34 |

Last Modified: | 01 Aug 2013 15:39 |

URI: | http://eprints.bbk.ac.uk/id/eprint/7921 |

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