The twofold look-ahead search (TLAS) was proposed as a general purpose search technique, and applied to single-criterion job shop scheduling. In the present study, this method is applied to multi-criterion scheduling problems with some modification, and illustrated by bi-criterion scheduling with mean tardiness and mean flowtime. Application circumstances are divided into two situations according to the scheduling objective, and TLAS is tested for each situation. From the computational results, the proposed method is found to generate higher performance schedules in comparison with other methods. Its algorithmic features and applicability to other problems are also discussed based on several experimental results.
