Reducing the Number of Changeover Constraints in a MIP Formulation of a   Continuous-Time Scheduling Problem
  In this paper, we develop a new formulation of changeover constraints for mixed integer programming problem (MIP) that emerges in solving a short-term production scheduling problem. The new model requires fewer constraints than the original formulation and this often leads to shorter computation time of a MIP solver. Besides that, the new formulation is more flexible if the time windows for changeover tasks are given. 
Pavel A. Borisovsky, Anton V. Eremeev, Josef Kallrath
math.OC