Complexity results on restricted instances of a paint shop problem for words
Authors:
P. Bonsma
Affiliation:
a Department of Applied Mathematics, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands b Department of Mathematics, BTU Cottbus, Germany c Fern Universität in Hagen, D-58084 Hagen, Germany
Abstract:
We study the following problem: an instance is a word with every letter occurring twice. A solution is a 2-coloring of its letters such that the two occurrences of every letter are colored with different colors. The goal is to minimize the number of color changes between adjacent letters.This is a special case of the paint shop problem for words, which was previously shown to be NP-complete. We show that this special case is also NP-complete and even APX-hard. Furthermore, derive lower bounds for this problem and discuss a transformation into matroid theory enabling us to solve some specific instances within polynomial time.
