A survey of the operational use of ILP models

In this note we demonstrate the growth of integer linear programming models in management decision-making by a small survey of published case studies from 1981 to 2001. The survey also shows the increased use of modelling software. A historical account of the origins of branch and bound is given. We have both spent many years teaching operational research and particularly linear and integer programming (LP and ILP) and we are interested in the extent that ILP and mixed integer programming (MIP) have changed in actual operational use over the last 30 years. This presentation is in two parts: the first about how we became involved in the subjects, starting with Ailsa Land, followed by Susan Powell; and the second about the increasingly successful use of ILP since 1977.