EFFICIENT MODELING OF PARTIAL RESOURCE EQUIVALENCE IN RESOURCE-TASK NETWORKS

The Resource-Task Network process representation provides a conceptual ly simple, unified framework for the development of mathematical progr amming formulations for multipurpose plant scheduling and design. Howe ver, the consideration of complex production processes sometimes leads to very large RTNs and, consequently, mixed integer optimisation prob lems that are difficult or impossible to solve using currently availab le techniques. One way of reducing the sim of the RTN representation o f a process is to identify functional equivalences among subsets of th e available resources, thereby allowing a more aggregate treatment of these resources. This paper provides the necessary theoretical-basis f or the exploitation of partial resource equivalence, which allows larg e RTNs to be reduced to smaller but completely equivalent ones. Such r eductions are particularly significant in problems involving many sequ ence-dependent changeovers. Examples illustrating these ideas and thei r impact are presented. (C) 1998 Elsevier Science Ltd. All rights rese rved.