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In the shortest superstring problem, we are given a set of strings {s 1 ,. .. , s k } and want to find a string that contains all s i as substrings and has minimum length. This is a classical problem in approximation and the best known approximation factor is 2 1 2 , given by Sweedyk [19] in 1999. Since then no improvement has been made, howerever two other(More)
We present the first 7/8-approximation algorithm for the maximum traveling salesman problem with triangle inequality. Our algorithm is deterministic. This improves over both the random-ized algorithm of Hassin and Rubinstein [3] with expected approximation ratio of 7/8 − O(n −1/2) and the deterministic (7/8 − O(n −1/3))-approximation algorithm of Chen and(More)
In this paper we propose and study a new complexity model for approximation algorithms. The main motivation are practical problems over large data sets that need to be solved many times for different scenarios, e.g., many multicast trees that need to be constructed for different groups of users. In our model we allow a preprocessing phase, when some(More)