Charge and reduce

String distance problems typically ask for a minimum number of permitted operations to transform one string into another. Such problems find application in a wide variety of areas, including error-correcting codes, parsing theory, speech recognition, and computational biology, to name a few. Here we...

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Bibliographic Details
Main Author: Abu-Khzam, Faisal N. (author)
Other Authors: Fernau, Henning (author), Langston, Micheal A. (author), Lee-Cultura, Serena (author), Stege, Ulrike (author)
Format: article
Published: 2015
Online Access:http://hdl.handle.net/10725/2773
http://dx.doi.org/10.1016/j.disopt.2010.10.003
http://www.sciencedirect.com/science/article/pii/S1572528610000708
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Summary:String distance problems typically ask for a minimum number of permitted operations to transform one string into another. Such problems find application in a wide variety of areas, including error-correcting codes, parsing theory, speech recognition, and computational biology, to name a few. Here we consider a classic string distance problem, the NP-complete String-to-String Correction problem, first studied by Wagner some 35 years ago. In this problem, we are asked whether it is possible to transform string x into string y with at most k operations on x, where permitted operations are single-character deletions and adjacent character exchanges. We prove that String-to-String Correction is fixed-parameter tractable, for parameter k, and present a simple fixed-parameter algorithm that solves the problem in O(2kn) time. We also devise a bounded search tree algorithm, and introduce a bookkeeping technique that we call charge and reduce . This leads to an algorithm whose running time is O(1.6181kn).