Notice

In a recent issue of this journal, Trypia presented a simple rule to determine the blending pattern and quantities for a multi‐product blending firm. This paper presents three variations of Trypia's model suitable for discussion in production management and mathematical modelling courses. First, it presents a generalized version of Trypia's problem leading to a linear programming formulation. Next a more realistic version of Trypia's problem including set‐up costs is presented together with a simple method for determining production sequence and quantities. Finally, the case of sequence dependent set‐up costs is discussed.