Introduction

Abstract

The purpose of these introductory comments is to set the stage and the context for the technical program. Their objective is to help the deliberations associated with it proceed in an effective manner, and to permit the limited available time to be used to best advantage. To do this, we need to focus attention on the most significant aspects of our particular subject, minimizing any diversions to peripheral questions, regardless of how interesting they are, or how important they may be in other contexts.