- Research Summary
Stochastic systems abound in real-world applications. Examples include
traffic systems, flexible manufacturing systems, computer-communication
systems, production lines, coherent lifetime systems, and flow networks.
Most of these systems can be modeled in terms of discrete events whose
occurrence causes the system to change from one state to another. In
designing, analyzing and operating such complex systems, one is interested
in
performance evaluation, sensitivity analysis and
optimization.
Sensitivity analysis is concerned with evaluating sensitivities
(gradients, Hessians, etc.) of performance measures with respect to
parameters of interest. It provides guidance for design and operational
decisions and plays a pivotal role in identifying the most significant
system parameters, as well as bottleneck subsystems.
Our group carries out research in the fields of probability of rare
events' estimation and stochastic optimization with emphasis on
simulation-based optimization. Our research programs are dedicated to
estimation of probabilities of rare events, like the probability of buffer
overflow in a queueing network of ATM type, probability of breakdown in a
highly reliable system and ruin probability in an insurance risk system.
This is cased on a novel approach developed at the Technion which is
called the cross-entropy (CE) method. Another research project is solving
NP-hard combinatorial optimization problems using a randomized algorithm
based on CE.