This volume constitutes the proceedings of the International Symposium on Design and Implementation of Symbolic Computation Systems (DISCO '93), held in Gmunden, Austria, in September 1993. The growing importance of systems for symbolic computation has greatly influenced the decision of organizing this third conference in the series: DISCO '93 focuses mainly on the most innovative methodological and technological aspects of the design and implementation of hardware and software systems for symbolic and algebraic computation, automated reasoning, geometric modeling and computation, and...