Abstract
This work focuses on the scheduling of a set of jobs with different release dates in a two-machine flowshop, where the blocking constraint is considered to minimize the sum of completion times. First, we provide the assignment and positional variable formulation for the problem under consideration and some mathematical models for particular cases of our problem. Subsequently, we derive four lower bounds based on linear relaxations. According to our formulations, we solve the studied problem exactly to provide optimal solutions. Computational experiments performed on large classes of instances show the effectiveness of the developed approaches.