Efficient offline algorithms for the bicriteria k-server problem and online applications

In this paper we consider the bicriteria version of the well-known k-server problem in which the cost incurred by an algorithm is evaluated simultaneously with respect to two different edge weightings. We show that it is possible to achieve the same competitive ratios of the previously known online algorithms with a dramatic improvement of the running time, i.e., from exponential to polynomial. Such results are obtained by exploiting new polynomial time algorithms able to find offline solutions whose costs differ from the optimal ones only of additive terms independent from the sequence of requests.