Abstract
In this paper we study the parameterized complexity of the Unique Coverage problem, a variant of the classic Set Cover problem. This problem admits several parameterizations and we show that all, except the standard parameterization and a generalization of it, are unlikely to be fixed-parameter tractable. We use results from extremal combinatorics to obtain the best-known kernel for Unique Coverage and the well-known color-coding technique of Alon et al. (J. ACM 42(4), 844–856, 1995) to show that a weighted version of this problem is fixed-parameter tractable.
Our application of color-coding uses an interesting variation of s-perfect hash families called (k,s)-hash families which were studied by Alon et al. (J. Comb. Theory Ser. A 104(1), 207–215, 2003) in the context of a class of codes called parent identifying codes (Barg et al. in SIAM J. Discrete Math. 14(3), 423–431, 2001). To the best of our knowledge, this is the first application of (k,s)-hash families outside the domain of coding theory. We prove the existence of such families of size smaller than the best-known s-perfect hash families using the probabilistic method (Alon and Spencer in The Probabilistic Method, Wiley, New York, 2000). Explicit constructions of such families of size promised by the probabilistic method is open.

Similar content being viewed by others
References
Alon, N., Spencer, J.H.: The Probabilistic Method. Interscience Series in Discrete Mathematics and Optimization. Wiley, New York (2000)
Alon, N., Yuster, R., Zwick, U.: Color-coding. J. ACM 42(4), 844–856 (1995)
Alon, N., Cohen, G., Krivelevich, M., Litsyn, S.: Generalized hashing and parent-identifying codes. J. Comb. Theory, Ser. A 104(1), 207–215 (2003)
Bar-Yehuda, R., Goldreich, O., Itai, A.: On the time-complexity of broadcast in multi-hop radio networks: an exponential gap between determinism and randomization. J. Comput. Syst. Sci. 45, 104–126 (1992)
Barg, A., Cohen, G., Encheva, S., Kabatiansky, G., Zémor, G.: A hypergraph approach to the identifying parent property: the case of multiple parents. SIAM J. Discrete Math. 14(3), 423–431 (2001)
Cesati, M.: Perfect Code is W[1]-complete. Inf. Process. Lett. 81(3), 163–168 (2002)
Chen, J., Kneis, J., Lu, S., Mölle, D., Richter, S., Rossmanith, P., Sze, S.-H., Zhang, F.: Randomized divide-and-conquer: improved path, matching, and packing algorithms. SIAM J. Comput. 38(6), 2526–2547 (2009)
Demaine, E.D., Feige, U., Hajiaghayi, M., Salavatipour, M.R.: Combination can be hard: approximability of the unique coverage problem. SIAM J. Comput. 38(4), 1464–1483 (2008)
Dom, M., Lokshtanov, D., Saurabh, S.: Incompressibility through colors and IDs. In: Proceedings of 36th International Colloquium of Automata, Languages and Programming (ICALP 2009). LNCS, vol. 5555. Springer, Berlin (2009)
Downey, R.G., Fellows, M.R.: Parameterized Complexity. Springer, New York (1999)
Erlebach, T., van Leeuwen, E.J.: Approximating geometric coverage problems. In: Proceedings of the 19th Annual ACM-SIAM Symposium on Discrete Algorithms (SODA 2008), pp. 1267–1276 (2008)
Flum, J., Grohe, M.: Parameterized Complexity Theory. Texts in Theoretical Computer Science. An EATCS Series. Springer, Berlin (2006)
Garey, M.R., Johnson, D.S.: Computers and Intractability. Freeman, San Francisco (1981)
Jukna, S.: Extremal Combinatorics. Springer, Berlin (2001)
Khuller, S., Moss, A., Naor, J.: The Budgeted Maximum Coverage problem. Inf. Process. Lett. 70(1), 39–45 (1999)
Mehlhorn, K.: On the program size of perfect and universal hash functions. In: Proceedings of the 23th IEEE Symposium on Foundations of Computer Science (FOCS), pp. 170–175. IEEE, New York (1982)
Misra, N., Raman, V., Saurabh, S., Sikdar, S.: Budgeted unique coverage and color-coding. In: Proceedings of the 4th Computer Science Symposium in Russia (CSR 2009). LNCS, vol. 5675, pp. 310–321. Springer, Berlin (2009)
Moser, H., Raman, V., Sikdar, S.: The parameterized complexity of the Unique Coverage problem. In: Proceedings of the 17th International Symposium on Algorithms and Computation (ISAAC 2007), vol. 4835, pp. 621–631 (2007)
Motwani, R., Raghavan, P.: Randomized Algorithms. Cambridge University Press, Cambridge (1995)
Niedermeier, R.: Invitation to Fixed-Parameter Algorithms. Oxford Lecture Series in Mathematics and Its Applications, vol. 31. Oxford University Press, Oxford (2006)
Schmidt, J., Siegel, A.: The spatial complexity of oblivious k-probe hash functions. SIAM J. Comput. 19(5), 775–786 (1990)
Acknowledgements
We thank Srikanth Srinivasan for useful discussions and an anonymous reviewer for comments that helped to improve the presentation.
Author information
Authors and Affiliations
Corresponding authors
Rights and permissions
About this article
Cite this article
Misra, N., Moser, H., Raman, V. et al. The Parameterized Complexity of Unique Coverage and Its Variants. Algorithmica 65, 517–544 (2013). https://doi.org/10.1007/s00453-011-9608-0
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00453-011-9608-0