Standardization in information systems

On a very abstract level, an information system consists of a set of system elements which communicate with each other. Communication is an unproductive operation, so the time needed to communicate data should be kept as short as possible and, to put it in monetary terms, the opportunity costs for communication should be kept small. Now, communicating data is more than just transmitting it, but it consists in large parts of converting data structures that are used by one system element into data structures that are used by another system element. Such conversion can be avoided, if the system elements use a common standard of data structures. Since establishing a standard at a system element incurs standardization costs, a decision maker has to check, if the cost savings gained by standardized communication outweigh the costs for installing the standard. In a recent paper, it is claimed that this so-called standardization problem is an NP-hard optimization problem. We will demonstrate that this is not true, but in fact the standardization problem can be solved in polynomial time by solving a minimum cut problem

Improved Lower Bounds for the Proportional Lot Sizing and Scheduling Problem

Where standard MIP--solvers fail to compute optimum objective function values for certain MIP--model formulations, lower bounds may be used as a point of reference for evaluating heuristics. In this paper, we compute lower bounds for the multi--level proportional lot sizing and scheduling problem with multiple machines (PLSP--MM). Four approaches are compared: Solving LP--relaxations of two different model formulations, solving a relaxed MIP--model formulation optimally, and solving a Lagrangean relaxation. Keywords: Multi--level lot sizing, scheduling, lower bounds, PLSP 1 Introduction The problem we are focussing at, can be described as follows: Several items are to be produced in order to meet some known (or estimated) dynamic demand without backlogs and stockouts. Precedence relations among these items define an acyclic gozinto--structure of the general type. In contrast to many authors who allow demand for end items only, now, demand may occur for all items including component ..

Stability Measures for Rolling Schedules with Applications to Capacity Expansion Planning, Master Production Scheduling, and Lot Sizing

rolling horizon nervousness rescheduling capacity expansion master production scheduling lot sizing