From the preface: "These proceedings contain 73 contributed papers selected from among those presented at the 13th IFIP Conference System Modelling and Optimization, Tokyo, Japan, August 31 - September 4, 1987, as well as 4 papers for the plenary sessions of the Conference. The aim of the conference was to discuss recent advances in the mathematical representation of engineering, sociotechnical, socioeconomic systems as well as in the optimization of their performances.