# PARALLEL SERVER SYSTEM

## Theorem (Harrison-Lopez ‘99)

## The following are equivalent.

## (I) the workload is one dimensional

## (iii) all servers communicate via basic activities

## In fact, the server-buffer graph with basic activities as

## edges is a tree and there is an asymptotically optimal

## (Policy proposed: W, ‘00,Squillante-Xia-Yao-Zhang ‘00;

## Proof of asymptotic optimality: Bell-W, ‘01)