Summary: On­Line Machine Covering
Yossi Azar 1 ,Leah Epstein 2
1 Dept. of Computer Science, Tel­Aviv University. ???
2 Dept. of Computer Science, Tel­Aviv University. y
Abstract. We consider the problem of scheduling a sequence of jobs to
m parallel machines as to maximize the minimum load over the machines.
This situation corresponds to a case that a system which consists of the
m machines is alive (i.e. productive) only when all the machines are alive,
and the system should be maintained alive as long as possible. It is well
known that any on­line deterministic algorithm for identical machines
has a competitive ratio of at least m and that greedy is an m competitive
algorithm. In contrast we design an on­line randomized algorithm which
is ~
O( p
m) competitive and a matching lower bound
of\Omega ( p
m) for any on­
line randomized algorithm. In the case where the jobs are polynomially
related we design an optimal O(log m) competitive randomized algorithm
and a matching tight lower bound for any on­line randomized algorithm.

Source: Azar, Yossi - School of Computer Science, Tel Aviv University
Epstein, Leah - Department of Mathematics, University of Haifa

Collections: Computer Technologies and Information Sciences; Mathematics