We present new combinatorial approximation algorithms for k-set cover. Previous approaches are based on extending the greedy algorithm by efficiently handling small sets. The new algorithms
further extend them by utilizing the natural idea of computing large packings of elements into sets of large size. Our results
improve the previously best approximation bounds for the k-set cover problem for all values of k ≥ 6. The analysis technique could be of independent interest; the upper bound on the approximation factor is obtained by
bounding the objective value of a factor-revealing linear program.
This work was partially supported by the European Union under IST FET Integrated Project 015964 AEOLUS.