Approximation algorithms for simple assembly line balancing problems

This work considers the three main optimization variants of the Simple Assembly Line Balancing problem (SALBP): SALBP-1, SALBP-2 and SALBP-E. These problems have origin in typical industrial production processes, where, to obtain a final product, partially ordered operations must be processed in workstations connected by a transportation equipment. Each version determines a different objective to be optimized: SALBP-1 focuses on minimizing the number of workstations while maintaining a certain production rate, SALBP-2 tries to maximize the production rate with a bounded number of workstations, and SALBP-E attempts to maximize the line efficiency. These problems are NP-hard and have been largely studied in the literature, however, the results on their approximability are scarce. This work approaches SALBP-1, SALBP-2 and SALBP-E, proving an equivalence on approximating in polynomial time SALBP-2 and a generalization of SALBP-E, and proposing very efficient polynomial time 2-approximation algorithms for each one of these three versions of SALBP.