ELSEVIER Int. J. Production Economics 46 47 11996) 109 118 international journal of product!on economics Modelling production scheduling systems Giinter Schmidt Universitiit Saarbriicken, lm Stadtwald, Gebiiude 30. D-6600 Saarhriicken D-66041, German)' Abstract Effective production scheduling plays a vital role in modern production processes. The complexity of scheduling requires efficient representation and solution methods for the underlying problems. Analysis and design of information systems for production scheduling challenges two research areas which are scheduling theory and software engineering. The approaches of either disciplines have to be harmonized. With this objective a model is presented which shows how object-oriented data structures and efficient problem solving can be combined. The model is generated with special regard to a restricted set of problems. Nevertheless, it can be easily customized to broader fields of applications. With this some object-oriented reference model is given for design and implementation of production scheduling software. Keywords: Production scheduling; Scheduling theory; Software engineering 1. Introduction The objective of this paper is to present a mod- elling approach integrating declarative repre- sentation and algorithmic solutions in the area of production scheduling. Problem representation and problem solution are strongly interconnec- ted, i.e, data structures and solution methods have to be designed interdependently [1]. In this paper we will present a reference model for production scheduling and show how problem description and problem solution can be integ- rated. To achieve this we follow the object- oriented modelling paradigm. Object-oriented modelling has its roots in object- oriented programming and is further developed in the area of Software Engineering. Essential for these kind of models are efficient algorithms to find the problem solution. For the domain of produc- tion scheduling these algorithms are mainly de- veloped at the interface of the areas of Operations Research and Computer Science also known as scheduling theory. The paper is organized as follows. In the next section we give a short survey about issues of pro- duction scheduling. Based on this in Section 3 we introduce objectives, models and methods to achieve the corresponding activities. Sections 4 and 5 are dedicated to building the object-oriented ref- erence model and validating it using an example from job shop scheduling. We finish with some conclusions. 2. Production scheduling and supporting activities Production scheduling is a part of the produc- tion management process which covers all plann- ing- and control-oriented activities to achieve a time, quality, and cost-effective production. Pro- duction scheduling on an aggregated level is carried out with the help of the production planning 0925-5273/96/$15.00 Copyright ~, 1996 ElsevierScienceB.V. All rights reserved SSDI 0925-5273(95)00019-4