 
Summary: Local Ratio: A Unified Framework for Approximation Algorithms
In Memoriam: Shimon Even 19352004
REUVEN BARYEHUDA AND KEREN BENDEL
Technion (Israel Institute of Technology)
ARI FREUND
IBM Haifa Research Lab
AND
DROR RAWITZ
TelAviv University
The local ratio technique is a methodology for the design and analysis of algorithms for
a broad range of optimization problems. The technique is remarkably simple and
elegant, and yet can be applied to several classical and fundamental problems
(including covering problems, packing problems, and scheduling problems). The local
ratio technique uses elementary math and requires combinatorial insight into the
structure and properties of the problem at hand. Typically, when using the technique,
one has to invent a weight function for a problem instance under which every
"reasonable" solution is "good." The local ratio technique is closely related to the
primaldual schema, though it is not based on weak LP duality (which is the basis of
the primaldual approach) since it is not based on linear programming.
In this survey we, introduce the local ratio technique and demonstrate its use in the
