Evaluation of heuristics for a branch and bound algorithm to minimize the makespan in a flowshop with blocking

Resumo

This paper has the objective to evaluate the use of different methods to obtain an initial solution for the branch and bound algorithm with the objective of minimizing the makespan in a flowshop with zero buffer environment. As the problem is known to be NP-Hard, the branch and bound algorithm may take long computational time to find the best solution. The use of an initial solution may reduce the computational time, by providing an initial upper bound. In this work, the efficiency of the use of an initial solution to the Branch and Bound algorithm was evaluated by comparison of the algorithms. The branch and bound algorithm used, as well as the lower bound, was proposed by Ronconi (2005). Four heuristic methods (MM, PF, wPF, and PW) were tested using a 180 problems data. Results show that the use of an initial solution does considerably reduce the computational time.