Abstract
Superstrings have many applications in data compression and genetics. However the decision version of the shortest superstring problem is N P-complete. In this paper we examine the complexity of approximating a shortest superstring. There are two basic measures of the approximations: the compression ratio and the approximation ratio. The well known and practical approximation algorithm is the sequential algorithm GREEDY. It approximates the shortest superstring with the compression ratio of 1/2 and with the approximation ratio of 4. Our main results are:
-
(1)
An NC algorithm which achieves the compression ratio of 1/4+ε.
-
(2)
The proof that the algorithm GREEDY is not parallelizable, the computation of its output is P-complete.
-
(3)
An improved sequential algorithm: the approximation ratio is reduced to 2.83. Previously it was reduced by Teng and Yao from 3 to 2.89.
-
(4)
The design of an RNC algorithm with constant approximation ratio and an NC algorithm with logarithmic approximation ratio.
Supported by DFG-Graduiertenkolleg “Parallele Rechnernetzwerke in der Produktionstechnik”, ME 872/4-1.
Supported in part by the EC Cooperative Action IC 1000 Algorithms for Future Technologies “ALTEC”.
Supported in part by Alexander von Humboldt-Stiftung and Volkswagen Stiftung.
Supported in part by the ESPRIT Basic Research Action No. 7141 (ALCOM II)
Preview
Unable to display preview. Download preview PDF.
Similar content being viewed by others
References
A. Arora, C. Lund, R. Motwani, M. Sudan, and M. Szegedy. Proof verification and hardness of approximation problems. 33rd FOCS, pp. 14–23, 1992.
A. Blum, T. Jiang, M. Li, J. Tromp, and M. Yannakakis. Linear approximation of shortest superstrings. 23rd STOC, pp. 328–336, 1991.
B. Berger, J. Rompel, and P. W. Shor. Efficient NC algorithms for set cover with applications to learning and geometry. 30th FOCS, pp. 54–59, 1989. The full version is to appear in J. Algorithms.
V. Chvatal. A greedy heuristic for the set-covering problem. Mathematics of Operations Research 4(1979), pp. 233–235.
J. Gallant, D. Maier, and J. Storer. On finding minimal length superstrings. Journal of Computer and System Sciences 20(1980), pp. 50–58.
M. R. Garey and D. S. Johnson. Computers and Intractability: A Guide to the Theory of NP-completeness. Freeman, New York, 1979.
R. Greenlaw, H. J. Hoover, and W. L. Ruzzo. A compendium of problems complete for P. Technical Report, University of Washington, 1991.
M. Li. Towards a DNA sequencing theory (Learning a string). 31st FOCS, 1990.
C. Lund and M. Yannakakis. On the hardness of approximating minimization problems. 25th STOC, 1993.
C. Papadimitriou and K. Steiglitz. Combinatorial Optimization: Algorithms and Complexity. Prentice-Hall, 1982.
C. Papadimitriou and M. Yannakakis. Optimization, approximation, and complexity classes. 20th STOC, pp. 229–234, 1988.
H. Peltola, H. Soderlund, J. Tarhio, and E. Ukkonen. Algorithms for some string matching problems arising in molecular genetics. IFIP, pp. 53–64, 1983.
J. Storer. Data Compression: Methods and theory. Computer Science Press, 1988.
J. Tarhio and E. Ukkonen. A Greedy approximation algorithm for constructing shortest common superstrings. Theoretical Computer Science 57(1988), pp. 131–145.
S-H. Teng and F. Yao. Approximating shortest superstrings. 34th FOCS, 1993.
J-S. Turner. Approximation algorithms for the shortest common superstring problem. Information and Computation 83(1989), pp. 1–20.
V. V. Vazirani. Parallel graph matching. In J. H. Reif, editor, Synthesis of Parallel Algorithms, chapter 18, pp. 783–811. Morgan Kaufmann, 1993.
Author information
Authors and Affiliations
Editor information
Rights and permissions
Copyright information
© 1994 Springer-Verlag Berlin Heidelberg
About this paper
Cite this paper
Czumaj, A., Gasieniec, L., Piotrów, M., Rytter, W. (1994). Parallel and sequential approximation of shortest superstrings. In: Schmidt, E.M., Skyum, S. (eds) Algorithm Theory — SWAT '94. SWAT 1994. Lecture Notes in Computer Science, vol 824. Springer, Berlin, Heidelberg. https://doi.org/10.1007/3-540-58218-5_9
Download citation
DOI: https://doi.org/10.1007/3-540-58218-5_9
Published:
Publisher Name: Springer, Berlin, Heidelberg
Print ISBN: 978-3-540-58218-2
Online ISBN: 978-3-540-48577-3
eBook Packages: Springer Book Archive