Is a Unit - Time Job Shop Not Easierthan
نویسندگان
چکیده
This paper gives the positive answer to the question posed in the title for a wide class of minimization criteria including the maximum completion time, maximum lateness , total completion time, total weighted completion time, total tardiness, total weighted tardiness, number of late jobs and the weighted number of late jobs. That is any scheduling problem for m identical parallel machines to minimize a criterion of the class reduces to a scheduling problem for an m-machine unit-time job shop to minimize the same criterion. Employing this general reduction we prove the NP-hardness of unit-time job-shop scheduling problems which had unknown complexity status before. The paper also presents a comprehensive picture of complexity results attained in unit-time job-shop scheduling and related open problems.
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