An Improved Formulation For Scheduling Multipurpose Batch Plants Using Synchronous Slots

Several continuous-time formulations in the literature address the most demanding problem of scheduling in multipurpose batch plants. These formulations can be broadly classified into two types based on the assignment binary variables. They are (i) Formulations with decoupling and (ii) ones without decoupling. The former rely on the postulation that decoupling the tasks from units reduces the number of assignment binaries. In contrary, the latter do not decouple the tasks from units but use the assignment binaries as such. In this work, we present a new, simpler and more efficient continuous-time mixed integer linear programming (MILP) formulation based on our proven opinion that formulations without decoupling necessarily require the same number of binaries that formulations with decoupling do.