Information systems science is rapidly advancing in many directions. Di­ versified ideas, methodologies, and techniques as well as applications have been conceived and developed. This series intends to discuss some of the recent advances in this field. In this volume, we cover four timely topics which are of great current interest. In each chapter, an attempt is made to familiarize the reader with some basic background information on the ad­ vances discussed. The emphasis of this volume is placed upon parallel pro­ gramming, data structure models in information system design, and the principles of L systems. One of the effective means to enhance computation performance is parallel information processing on multiprocessor systems. In Chapter I, V. E. Kotov discusses the practical aspects of parallel programming. He is concerned with the languages and methods of parallel programming, per­ formance an~lysis, and automatic synthesis of parallel programs. In Chapter 2, A. S. Narin'yani presents the formal theory of parallel computations. These two chapters attempt to correlate and classify various methods in parallel programming, thus providing the reader with a unified approach to this important subject matter. Data structures play an important role in information system design.