1 - Introduction

Summary

From clarity to efficiency: systematic program design

At the center of computer science, there are two major concerns of study: what to compute, and how to compute efficiently. Problem solving involves going from clear specifications for “what” to efficient implementations for “how”. Unfortunately, there is generally a conflict between clarity and efficiency, because clear specifications usually correspond to straightforward implementations, not at all efficient, whereas efficient implementations are usually sophisticated, not at all clear. What is needed is a general and systematic method to go from clear specifications to efficient implementations.

We give example problems from various application domains and discuss the challenges that lead to the need for a general and systematic method. The example problems are for database queries, hardware design, image processing, string processing, graph analysis, security policy frameworks, program analysis and verification, and mining semi-structured data. The challenges are to ensure correctness and efficiency of developed programs and to reduce costs of development and maintenance.

Example problems and application domains

Database queries. Database queries matter to our everyday life, because databases are used in many important day-to-day applications. Consider an example where data about professors, courses, books, and students are stored, and we want to find all professor-course pairs where the professor uses any of his own books as the textbook for the course and any of his own students as the teaching assistant for the course.