386 This work is licensed under a Creative Commons Attribution 4.0 International License IHJPAS. 37 (1) 2024 Ibn Al-Haitham Journal for Pure and Applied Sciences Journal homepage: jih.uobaghdad.edu.iq PISSN: 1609-4042, EISSN: 2521-3407 1Nagham Muosa Neamah 2,*Bayda Atiya Kalaf 3Hamiden Abd El-Wahed Khalifa 1,2Department of Mathematics, College of Education for Pure Sciences, Ibn Al โ€“ Haitham, University of Baghdad Iraq 3Department of Mathematics, College of Science and Arts, Qassim University, Al-Badaya 51951,Saudi Arabia. 3Department of Operations and Management Research, Faculty of Graduate Studies for Statistical Research, Cairo University, Giza 12613, Egypt *Corresponding Author. baydaa.a.k@ihcoedu.uobaghdad.edu.iq Abstract Machine scheduling problems (MSP) are considered as one of the most important classes of combinatorial optimization problems. In this paper, the problem of job scheduling on a single machine is studied to minimize the multi objective and multi objective function. This objective function is: total completion time, total lead time and maximum tardiness time, respectively, which are formulated as (โˆ‘๐‘ช๐’‹ , โˆ‘ ๐‘ฌ๐’‹ , ๐‘ป๐’Ž๐’‚๐’™) are formulated. In this study, a mathematical model is created to solve the research problem. This problem can be divided into several sub- problems and simple algorithms have been found to find the solutions to these sub-problems and compare them with efficient solutions. For this problem, some rules that provide efficient solutions have been proved and some special cases have been introduced and proved since the problem is an NP-hard problem to find some efficient solutions that are efficient for the discussed problem 1// ๐น(โˆ‘๐‘ช๐’‹ , โˆ‘๐‘ฌ๐’‹ , ๐‘ป๐’Ž๐’‚๐’™), and good or optimal solutions for the multi- objective functions 1// โˆ‘๐ถ๐‘— + โˆ‘๐ธ๐‘— + ๐‘‡๐‘š๐‘Ž๐‘ฅ,, and emphasize the importance of the dominance rule (DR), which can be applied to this problem to improve efficient solutions. Keywords: Maximum Tardiness, Multi-Criteria, Multi-Objective, Total Completion Times, Total Earliness Time. Received 13 December 2022, Received 6 January 2023, Accepted 13 March 2023, Published 20 January 2024 Solving the Multi-criteria, Total Completion Time, Total Earliness Time, and Maximum Tardiness Problem doi.org/10.30526/37.1.3094 https://creativecommons.org/licenses/by/4.0/ https://jih.uobaghdad.edu.iq/index.php/j/index#1609-4042 https://jih.uobaghdad.edu.iq/index.php/j/index#2521-3407 mailto:baydaa.a.k@ihcoedu.uobaghdad.edu.iq https://orcid.org/0000-0001-5393-4083 mailto:nagham2182011@gmail.com https://orcid.org/0000-0003-1136-0055 mailto:baydaa.a.k@ihcoedu.uobaghdad.edu.iq https://orcid.org/0000-0002-8269-8822 mailto:Ha.Ahmed@qu.edu.sa IHJPAS. 37 (1) 2024 387 1. Introduction Scheduling involves distributing a set number of resources over a period of time to various tasks[1]. One or more objectives may be optimized as a result of this decision-making process. as well as, the Scheduling problem is defined as the arrangement of entities (people, tasks, vehicles, lecture, etc.) into a pattern in space-time in such a way that constraints are satisfied and certain goals are achieved [2-4]. Up until the late 1980s, mainstream research has concentrated on a certain single object problem. When more than one objective (criteria) is needed, scheduling problems become more difficult to model and solve. It is frequently implausible that different objectives will be best served by the same set of decision variables [5-8]. As a result, there is a trade-off between the multiple objectives. This type of problem is known as a multi-objective scheduling problem. Multi-objective scheduling problems are the term used to describe this kind of problem [9]. A set of Pareto optimal solutions (Efficient solutions), rather than a single optimal solution, are established using multi-criteria optimization based on competing objective functions. This set includes one (many) solution(s) that no other solution(s) is better with respect to objective functions[[10-14]. The most important literature survey for the last eight years. [15] discussed the multi-criteria in order to establish a collection of efficient solutions for the general problem, and scheduling problems that are researched on a single machine are considered. 1// (โˆ‘๐‘ช๐’‹, โˆ‘๐‘ป๐’‹, ๐‘ป๐‘ด๐’‚๐’™) , 1// ๐‘ญ(โˆ‘๐‘ช๐’‹, โˆ‘๐‘ฌ๐’‹ , ๐‘ฌ๐‘ด๐’‚๐’™) , 1// โˆ‘๐‘ช๐’‹ + โˆ‘๐‘ป๐’‹ + ๐‘ป๐‘ด๐’‚๐’™ , 1// โˆ‘๐‘ช๐’‹ + โˆ‘๐‘ฌ๐’‹ + ๐‘ป๐‘ด๐’‚๐’™. [16] examined the multi- objective problem, which is the sum of completion time, tardiness, earliness, and late work. 1// โˆ‘ (๐‘ฌ๐’‹ + ๐‘ป๐’‹ + ๐‘ช๐’‹ + ๐‘ผ๐’‹ + ๐‘ฝ๐’‹) ๐’ =๐Ÿ ,1//โˆ‘ (๐œถ๐‘ฑ๐‘ฌ๐’‹ + ๐œท๐’‹๐‘ป๐’‹ + ๐œฝ๐’‹๐‘ช๐’‹ + ๐œธ๐’‹๐‘ผ๐’‹ +๐Ž๐’‹๐‘ฝ๐’‹) ๐’ =๐Ÿ ,1/๐‘บ๐’‡/ โˆ‘ (๐œถ๐’‹๐’‡๐‘ฌ๐’‹๐’‡ + ๐’ =๐Ÿ ๐œท๐’‹๐’‡๐‘ป๐’‹๐’‡ + ๐œฝ๐’‹๐’‡๐‘ช๐’‹๐’‡ + ๐œธ๐’‹๐’‡๐‘ผ๐’‹๐’‡ +๐Ž๐’‹๐’‡๐‘ฝ๐’‹๐’‡). They suggested an Upper Bound (limits) UB and a Lower Boundary (limits) LB be used in the application of the Branch and Bound method. [17] studied the multi-criteria (โˆ‘๐‘ช๐’‹ , ๐‘ป๐’Ž๐’‚๐’™, ๐‘น๐‘ณ), multi-objective function (โˆ‘๐‘ช๐’‹ + ๐‘ป๐’Ž๐’‚๐’™ + ๐‘น๐‘ณ) and founded the optimal solution by using the BAB method with and without DR then using some heuristic methods. [18] introduced a heuristic algorithm to reduce the (โˆ‘๐‘ช๐’‹ + ๐‘ฌ๐’Ž๐’‚๐’™ + ๐‘ป๐’Ž๐’‚๐’™) in a single machine scheduling. In this paper, survey the tricriteria scheduling problem and begin with some basic scheduling concepts of multi-criteria problems, and basic rules are given in section 1. Section 2 provides information on problem formulation, analysis, and various algorithms. The Dominance Rule is described in section 3. In section 4 by proving several rules, we show there exists is an effective solution to our problem. The conclusions is given in section 5 and upcoming works. 2. Significant Notations. In this paper, the following notations are used: ๐‘ต: jobs set s. t. ๐‘ = {1,2, โ€ฆ , ๐‘›}. ๐’: number of available jobs. ๐’‘๐’‹: Ttime of the job ๐‘—โ€ฒ๐‘  processing, which means it must be processed for a period of length ๐’‘๐’‹. ๐’…๐’‹: The due date for job ๐‘— (or the jobsโ€™ due date), the optimal date for finishing the jobs; job termination after the deadline is allowed but will result in a penalty. IHJPAS. 37 (1) 2024 388 ๐’”๐’‹: The Job's slack time for ๐‘— s. t. ๐‘ ๐‘— = ๐‘‘๐‘— โˆ’ ๐‘๐‘—. ๐‘ช๐’‹: The job ๐‘—โ€ฒ๐‘  completion time where ๐ถ๐‘— = โˆ‘ ๐‘๐‘˜ ๐‘— ๐‘˜=1 . ๐‘ณ๐’‹: The lateness time of jobs, s. t. ๐ฟ๐‘— = โˆ’(๐‘‘๐‘— โˆ’ ๐ถ๐‘—) = ๐ถ๐‘— โˆ’ ๐‘‘๐‘—. ๐‘ฌ๐’‹: The earliness of job ๐‘— s. t. ๐ธ๐‘— = ๐‘š๐‘Ž๐‘ฅ {โˆ’๐ฟ๐‘— , 0} = ๐‘š๐‘Ž๐‘ฅ{๐‘‘๐‘— โˆ’ ๐ถ๐‘— , 0} . ๐‘ป๐’‹: The tardiness of job ๐‘— s. t. ๐‘‡๐‘— = ๐‘š๐‘Ž๐‘ฅ {๐ฟ๐‘— , 0} = ๐‘š๐‘Ž๐‘ฅ{๐ถ๐‘— โˆ’ ๐‘‘๐‘—, 0} . โˆ‘๐‘ช๐’‹: Total completion time. โˆ‘๐‘ฌ๐’‹: Total earliness time. ๐‘ป๐’Ž๐’‚๐’™ : Maximum tardiness s. t. ๐‘‡๐‘š๐‘Ž๐‘ฅ = ๐‘š๐‘Ž๐‘ฅ๐‘—โˆˆ๐‘{๐‘‡๐‘—}. ๐‘ญ: The โ‚ฑ-problem's objective function. ๐‘ญ๐Ÿ: The (๐‘†โ‚ฑ)-problem's objective function. Shortest Processing Tim (SPT): Jobs are Sequencing in non-decreasing order of the processing times ๐‘๐‘— (i. e. ๐‘1 โ‰ค ๐‘2 โ‰ค โ‹ฏ โ‰ค ๐‘๐‘›), this rule is well known to minimize โˆ‘๐ถ๐‘— for problem 1// โˆ‘๐ถ๐‘— [8]. Earliest Due Date (EDD): Jobs are sequenced in non-decreasing order of their due dates ๐‘‘๐‘—(i. e. ๐‘‘1 โ‰ค ๐‘‘2 โ‰ค โ‹ฏ โ‰ค ๐‘‘๐‘›), this rule used to minimize ๐‘‡๐‘š๐‘Ž๐‘ฅ for problem 1// ๐‘‡๐‘š๐‘Ž๐‘ฅ [19]. Minimum Slack Time (MST): Jobs are sequenced in non-decreasing order of their slack time ๐‘ ๐‘— = ๐‘‘๐‘— โˆ’ ๐‘๐‘— (i. e. ๐‘ 1 โ‰ค ๐‘ 2 โ‰ค โ‹ฏ โ‰ค ๐‘ ๐‘›). To minimize ๐ธ๐‘š๐‘Ž๐‘ฅ using this rule [20]. Efficient Solution (EFSO): A feasible schedule ๐›ผโˆ— is known as Pareto optimal or ( non- dominated) If there is absolutely no feasible schedule ๐›ผ, then the set of feasible schedules with regard to the criteria โ„Ž1 , โ„Ž2 and โ„Ž3 such that โ„Ž1(๐›ผ) โ‰ค โ„Ž1(๐›ผ โˆ—) , โ„Ž2(๐›ผ) โ‰ค โ„Ž2(๐›ผ โˆ—) and โ„Ž3(๐›ผ) โ‰ค โ„Ž3(๐›ผ โˆ—), are satisfied with at least one of the inequalities [21]. 3. Mathematical Formulation In this section, the three-criteria scheduling problem (1// ๐‘ญ(โˆ‘๐‘ช๐’‹ , โˆ‘ ๐‘ฌ๐’‹ , ๐‘ป๐’Ž๐’‚๐’™)) to be studied will be described. Let the number of jobs available at time 0 be represented by ๐‘ = {1,2, โ€ฆ , ๐‘›}, (i. e, ๐‘Ÿ๐‘— = 0 for all ๐‘—) and need processing on just one machine. For each job, ๐‘— has a processing time ๐‘๐‘— and a due date ๐‘‘๐‘—, given a list of jobs in the sequence ๐›ผ = (๐›ผ1, ๐›ผ2, โ€ฆ , ๐›ผ๐‘›), the earliest completion time possible ๐ถ๐‘— = โˆ‘ ๐‘๐›ผ๐‘˜ ๐‘› ๐‘˜=1 , the tardiness of job ๐‘—, ๐‘‡๐‘— = ๐‘š๐‘Ž๐‘ฅ {๐ถ๐‘— โˆ’ ๐‘‘๐›ผ๐‘— , 0} , the earliness of job ๐‘—, ๐ธ๐‘— = ๐‘š๐‘Ž๐‘ฅ {๐‘‘๐›ผ๐‘— โˆ’ ๐ถ๐‘— , 0}. The aim of this problem is finding a schedule ฮฑ โˆˆ ๐’ฎ to find a schedule, (where ๐’ฎ is the set of all possible feasible schedules; where a feasible schedule means it satisfies all the constraints of the problem โ‚ฑ) that minimizes the multi-criteria (โˆ‘๐ถ๐‘— , โˆ‘๐ธ๐‘— , ๐‘‡๐‘š๐‘Ž๐‘ฅ), which is denoted by (๐‘†๐ถ๐‘†๐ธ๐‘‡), can be formulated mathematically as follows: ๐‘€๐‘–๐‘›{โˆ‘๐ถ๐‘—, โˆ‘๐ธ๐‘— , ๐‘‡๐‘š๐‘Ž๐‘ฅ} s. t. ๐ถ1 = ๐‘๐›ผ1 ๐ถ๐‘— โ‰ฅ ๐‘๐›ผ๐‘— ๐‘— = 1,2, โ€ฆ , ๐‘› ๐ถ๐‘— = ๐ถ๐›ผ(๐‘—โˆ’1) + ๐‘๐›ผ๐‘— ๐‘— = 2,โ€ฆ , ๐‘› ๐‘‡๐‘— โ‰ฅ ๐ถ๐‘— โˆ’ ๐‘‘๐›ผ๐‘— ๐‘— = 1,2, โ€ฆ , ๐‘› ๐ธ๐‘— โ‰ฅ ๐‘‘๐›ผ๐‘— โˆ’ ๐ถ๐‘— ๐‘— = 1,2, โ€ฆ , ๐‘› ๐‘‡๐‘— โ‰ฅ 0, ๐ธ๐‘— โ‰ฅ 0 ๐‘— = 1,2, โ€ฆ , ๐‘›} โ€ฆ(๐‘†๐ถ๐‘†๐ธ๐‘‡). IHJPAS. 37 (1) 2024 389 Where ๐›ผ๐‘— indicate where job ๐‘— falls in the ordering ฮฑ and ๐’ฎ represents the collection of all schedules. Finding the set of all efficient solutions to the problem (๐‘†๐ถ๐‘†๐ธ๐‘‡) is challenging since itโ€™s an NP-hard problem (because the problem 1// โˆ‘ ๐ธ๐‘— ๐‘› ๐‘—=1 is NP-hard [22]). Proposition (1): There is an efficient schedule for the problem (๐‘†๐ถ๐‘†๐ธ๐‘‡) that satisfies the SPT rule. Proof: (a) first, assume that ๐‘๐‘– โ‰  ๐‘๐‘— for all ๐‘–, ๐‘—. The unique sequence SPT, (๐‘†๐‘ƒ๐‘‡โˆ—) provides the bare minimum of โˆ‘๐ถ๐‘—. As a result, no sequence exists ๐›ฟ โ‰  ๐‘†๐‘ƒ๐‘‡โˆ— s.t. โˆ‘๐ถ๐‘—(๐›ฟ) โ‰ค โˆ‘๐ถ๐‘— (๐‘†๐‘ƒ๐‘‡ โˆ—), โˆ‘๐ธ๐‘— (๐›ฟ) โ‰ค โˆ‘๐ธ๐‘— (๐‘†๐‘ƒ๐‘‡ โˆ—), and ๐‘‡๐‘š๐‘Ž๐‘ฅ(๐›ฟ) โ‰ค ๐‘‡๐‘š๐‘Ž๐‘ฅ(๐‘†๐‘ƒ๐‘‡ โˆ—) (1) The presence of one or more strict inequalities. (b) If there is more than one sequence SPT (the processing times of jobs are equal), assume ๐‘†๐‘ƒ๐‘‡โˆ— be a sequence that satisfies the rule of SPT and jobs with equal processing times in the EDD and MST sequence. If a set of jobs that are to be early or partially early is specified, then this EDD and MST order minimized โˆ‘๐ธ๐‘—. Note that if the event is several jobs at the same processing times, the due date is considered identical, or slack times, then ๐‘†๐‘ƒ๐‘‡โˆ— is not unique. Show that each ๐‘†๐‘ƒ๐‘‡โˆ—- sequence is an efficient, sequence that does not satisfy the SPT rule which cannot dominate an ๐‘†๐‘ƒ๐‘‡โˆ— sequence by (1.1). If ฮด is an SPT-sequences but not an SPT* sequence, it cannot dominate ๐‘†๐‘ƒ๐‘‡โˆ— since โˆ‘๐ถ๐‘—(๐›ฟ) = โˆ‘๐ถ๐‘—(๐‘†๐‘ƒ๐‘‡ โˆ—), โˆ‘๐ธ๐‘— (๐‘†๐‘ƒ๐‘‡ โˆ—) โ‰ค โˆ‘๐ธ๐‘— (๐›ฟ) and ๐‘‡๐‘š๐‘Ž๐‘ฅ(๐‘†๐‘ƒ๐‘‡ โˆ—) โ‰ค ๐‘‡๐‘š๐‘Ž๐‘ฅ(๐›ฟ) by virtue of the EDD and MST rule. Hence all the ๐‘†๐‘ƒ๐‘‡โˆ— sequences are efficient. As mentioned in proposition (1), shown that the SPT rule is efficient for the problem (๐‘†๐ถ๐‘†๐ธ๐‘‡) but the EDD rule does not, as shown in the example below. Example (1): Suppose the problem (๐‘†๐ถ๐‘†๐ธ๐‘‡) has the following data in Table 1: Table 1. The data of ๐‘๐‘— , ๐‘‘๐‘— , and ๐‘ ๐‘— for problem (๐‘†๐ถ๐‘†๐ธ๐‘‡) Job1 Job2 Job3 Job4 Job5 ๐‘๐‘— 2 5 7 5 8 ๐‘‘๐‘— 6 9 8 11 14 ๐‘ ๐‘— 4 4 1 6 6 A feasible schedule is provided by the SPT rule(1,2,4,3,5) and (1,4,2,3,5), hence (โˆ‘๐ถ๐‘— , โˆ‘๐ธ๐‘— , ๐‘‡๐‘š๐‘Ž๐‘ฅ) = (67,6,13) from ๐‘†๐‘ƒ๐‘‡โˆ— order (1,2,4,3,5) and (โˆ‘๐ถ๐‘— , โˆ‘๐ธ๐‘— , ๐‘‡๐‘š๐‘Ž๐‘ฅ) = (67,7,13) from SPT order (1,4,2,3,5), it is clear that in the ๐‘†๐‘ƒ๐‘‡โˆ—sequence the tasks (2,4) are arranged with equal processing time in the rule of the MST or EDD. But EDD rule (1,3,2,4,5) with (โˆ‘๐ถ๐‘— , โˆ‘๐ธ๐‘— , ๐‘‡๐‘š๐‘Ž๐‘ฅ) = (71,4,13) and MST rule (3,1,2,4,5) with (โˆ‘๐ถ๐‘—, โˆ‘๐ธ๐‘— , ๐‘‡๐‘š๐‘Ž๐‘ฅ) = (76,1,13) hence ๐‘†๐‘ƒ๐‘‡โˆ—the sequence gives an efficient solution for the problem (๐‘†๐ถ๐‘†๐ธ๐‘‡). For the problem(๐‘†๐ถ๐‘†๐ธ๐‘‡), we can deduce seven sub problems (๐‘†โ‚ฑ๐‘–) for ๐‘– = 1 to 7: IHJPAS. 37 (1) 2024 390 1) 1//๐ฟ๐‘’๐‘ฅ(โˆ‘๐ถ๐‘—, โˆ‘๐ธ๐‘— , ๐‘‡๐‘š๐‘Ž๐‘ฅ) problem ๐‘†โ‚ฑ1. 2) 1//๐ฟ๐‘’๐‘ฅ(โˆ‘๐ถ๐‘—, ๐‘‡๐‘š๐‘Ž๐‘ฅ , โˆ‘๐ธ๐‘—) problem ๐‘†โ‚ฑ2. 3) 1//๐ฟ๐‘’๐‘ฅ(๐‘‡๐‘š๐‘Ž๐‘ฅ , โˆ‘๐ถ๐‘— , โˆ‘๐ธ๐‘—) problem ๐‘†โ‚ฑ3. 4) 1//๐ฟ๐‘’๐‘ฅ(๐‘‡๐‘š๐‘Ž๐‘ฅ , โˆ‘๐ธ๐‘— , โˆ‘๐ถ๐‘—) problem ๐‘†โ‚ฑ4. 5) 1//๐ฟ๐‘’๐‘ฅ(โˆ‘๐ธ๐‘— , โˆ‘๐ถ๐‘— , ๐‘‡๐‘š๐‘Ž๐‘ฅ) problem ๐‘†โ‚ฑ5. 6) 1//๐ฟ๐‘’๐‘ฅ( โˆ‘๐ธ๐‘— , ๐‘‡๐‘š๐‘Ž๐‘ฅ , โˆ‘๐ถ๐‘—) problem ๐‘†โ‚ฑ6. 7) 1// (โˆ‘๐ถ๐‘— + โˆ‘๐ธ๐‘— + ๐‘‡๐‘š๐‘Ž๐‘ฅ) problem ๐‘†โ‚ฑ7. (1) 1// ๐‘ณ๐’†๐’™(โˆ‘๐‘ช๐’‹, โˆ‘๐‘ฌ๐’‹, ๐‘ป๐’Ž๐’‚๐’™)(๐‘บโ‚ฑ๐Ÿ): The definition of this problem is as follows: ๐‘€๐‘–๐‘› {๐‘‡๐‘š๐‘Ž๐‘ฅ} s. t. โˆ‘ ๐ถ๐‘— ๐‘› ๐‘—=1 = ๐ถโˆ— where ๐ถโˆ— = โˆ‘ ๐ถ๐‘—(๐‘†๐‘ƒ๐‘‡) ๐‘› ๐‘—=1 โˆ‘ ๐ธ๐‘— ๐‘› ๐‘—=1 โ‰ค ๐ธ, ๐ธ โˆˆ [โˆ‘ ๐ธ๐‘— ๐‘› ๐‘—=1 (๐‘€๐‘†๐‘‡),โˆ‘ ๐ธ๐‘— ๐‘› ๐‘—=1 (๐‘†๐‘ƒ๐‘‡)]} (๐‘†โ‚ฑ1). Since the most important function in this problem (Sโ‚ฑ1), โˆ‘ ๐ถ๐‘— ๐‘› ๐‘—=1 , should be optimal, the following easy algorithm produces the best possible outcome. Algorithm (๐‘บ๐‘ช๐‘บ๐‘ฌ๐‘ป๐Ÿ) for 1//๐‘ณ๐’†๐’™(โˆ‘๐‘ช๐’‹, โˆ‘๐‘ฌ๐’‹, ๐‘ป๐’Ž๐’‚๐’™) ๐ฉ๐ซ๐จ๐›๐ฅ๐ž๐ฆ (๐‘บโ‚ฑ๐Ÿ). ST1: is the Sequencing of jobs according to the SPT rule and the computation(โˆ‘๐‘ช๐’‹, โˆ‘๐‘ฌ๐’‹, ๐‘ป๐’Ž๐’‚๐’™). ST2: If there are jobs with equal processing times, then order these jobs: (a) using the MST rule and the calculation (โˆ‘๐‘ช๐’‹, โˆ‘๐‘ฌ๐’‹, ๐‘ป๐’Ž๐’‚๐’™). (b) using the EDD rule and the calculation(โˆ‘๐‘ช๐’‹, โˆ‘๐‘ฌ๐’‹, ๐‘ป๐’Ž๐’‚๐’™). ST3: If more than one SPT schedule appeared, then choose the schedule with minimum โˆ‘๐‘ฌ๐’‹ and ๐‘ป๐’Ž๐’‚๐’™ . Note: Same as an example (1) for ๐‘†โ‚ฑ1. (2) 1//๐‘ณ๐’†๐’™(โˆ‘๐‘ช๐’‹ , ๐‘ป๐’Ž๐’‚๐’™, โˆ‘๐‘ฌ๐’‹)(๐‘บโ‚ฑ๐Ÿ): This problem is defined as follows: ๐‘€๐‘–๐‘› {โˆ‘๐ธ๐‘—} s. t. โˆ‘ ๐ถ๐‘— ๐‘› ๐‘—=1 = ๐ถโˆ— where ๐ถโˆ— = โˆ‘ ๐ถ๐‘—(๐‘†๐‘ƒ๐‘‡) ๐‘› ๐‘—=1 ๐‘‡๐‘š๐‘Ž๐‘ฅ โ‰ค ๐‘‡, ๐‘‡ โˆˆ [๐‘‡๐‘š๐‘Ž๐‘ฅ(๐ธ๐ท๐ท), ๐‘‡๐‘š๐‘Ž๐‘ฅ(๐‘†๐‘ƒ๐‘‡)] } (๐‘†โ‚ฑ2). The problem (Sโ‚ฑ2)with โˆ‘ ๐ถ๐‘— ๐‘› ๐‘—=1 is the most important function, it must be optimal, so the easy algorithm ๐‘บ๐‘ช๐‘บ๐‘ฌ๐‘ป๐Ÿ that gives us the best result for (Sโ‚ฑ2). (3) 1//๐‘ณ๐’†๐’™(๐‘ป๐’Ž๐’‚๐’™, โˆ‘๐‘ช๐’‹, โˆ‘๐‘ฌ๐’‹)(๐‘บโ‚ฑ๐Ÿ‘): This problem is defined as follows: IHJPAS. 37 (1) 2024 391 ๐‘€๐‘–๐‘›โˆ‘ ๐ธ๐‘— ๐‘› ๐‘—=1 s. t. ๐‘‡๐‘š๐‘Ž๐‘ฅ = ๐‘‡ โˆ— where ๐‘‡โˆ— = ๐‘‡๐‘š๐‘Ž๐‘ฅ(๐ธ๐ท๐ท) โˆ‘ ๐ถ๐‘— โ‰ค ๐ถ, ๐ถ๐‘› ๐‘—=1 โˆˆ [โˆ‘ ๐ถ๐‘— ๐‘› ๐‘—=1 (๐‘†๐‘ƒ๐‘‡),โˆ‘ ๐ถ๐‘—(๐ธ๐ท๐ท)] ๐‘› ๐‘—=1 } (Sโ‚ฑ3). Given that ๐‘‡๐‘š๐‘Ž๐‘ฅ is a more important function in this problem (Sโ‚ฑ3) and should be optimal, the following algorithm offers the best solution. Algorithm (๐‘บ๐‘ช๐‘บ๐‘ฌ๐‘ป๐Ÿ) for 1//๐‘ณ๐’†๐’™(๐‘ป๐’Ž๐’‚๐’™, โˆ‘๐‘ช๐’‹, โˆ‘๐‘ฌ๐’‹) ๐ฉ๐ซ๐จ๐›๐ฅ๐ž๐ฆ (๐‘บโ‚ฑ๐Ÿ‘). ST1: Arrange the jobs according to the rule of EDD and calculate ๐‘ป๐’Ž๐’‚๐’™(๐‘ฌ๐‘ซ๐‘ซ) = ๐‘ป โˆ—. ST2: Calculated ๐ท๐‘– = ๐‘‘๐‘– + ๐‘‡ โˆ—, for all in ๐‘ ๐‘คโ„Ž๐‘’๐‘Ÿ๐‘’ ๐‘ = {1, โ€ฆ , ๐‘›}. ST3: Suppose ๐‘ก = โˆ‘ ๐‘๐‘–๐‘–โˆˆ๐‘ and ๐พ equals ๐‘›. ST4: Finding a job ๐‘— using the Smith backward algorithm and satisfying ๐ท๐‘— โ‰ฅ ๐‘ก, ๐‘๐‘— โ‰ฅ ๐‘๐‘– (Choose the job ๐‘— with the largest due date if there is a tie). Assign position ๐พto job ๐‘—. ST5: Assign the variables ๐‘ก = ๐‘ก โˆ’ ๐‘๐‘— , ๐‘ = ๐‘ โˆ’ {๐‘—} and ๐พ = ๐พ โˆ’ 1; if ๐พ = 1 proceed to step 6; if not, proceed to step 4. ST6: Find ๐‘‡๐‘š๐‘Ž๐‘ฅ , โˆ‘๐ถ๐‘— and โˆ‘๐ธ๐‘— for the sequence that results. Example (2): Consider the data for the problem ๐‘†โ‚ฑ3 in Table 2. Table 2. The data of ๐‘๐‘— , ๐‘‘๐‘— , and ๐‘ ๐‘— for problem ๐‘†โ‚ฑ3 Job1 Job2 Job3 Job4 ๐‘๐‘— 9 3 7 2 ๐‘‘๐‘— 12 5 9 10 ๐‘ ๐‘— 3 2 2 8 Hence the (EDD) schedule (2,3,4,1) gives (๐‘‡๐‘š๐‘Ž๐‘ฅ, โˆ‘๐ถ๐‘—, โˆ‘๐ธ๐‘—) = (46,2,9). ๐‘‡๐‘š๐‘Ž๐‘ฅ(๐ธ๐ท๐ท) = ๐‘‡โˆ—, ๐‘ก = 21 , ๐ท๐‘– = ๐‘‘๐‘– + ๐‘‡ โˆ— = (21,14,18,19). The schedule (4,2,3,1) is given by Smith's backward algorithm with (๐‘‡๐‘š๐‘Ž๐‘ฅ, โˆ‘๐ถ๐‘— , โˆ‘๐ธ๐‘—) = (40,8,9). (4) 1//๐‘ณ๐’†๐’™(๐‘ป๐’Ž๐’‚๐’™, โˆ‘๐‘ฌ๐’‹, โˆ‘๐‘ช๐’‹)(๐‘บโ‚ฑ๐Ÿ’): This problem is defined as follows: ๐‘€๐‘–๐‘›โˆ‘ ๐ถ๐‘— ๐‘› ๐‘—=1 s. t. ๐‘‡๐‘š๐‘Ž๐‘ฅ = ๐‘‡โˆ— where ๐‘‡โˆ— = ๐‘‡๐‘š๐‘Ž๐‘ฅ(๐ธ๐ท๐ท) โˆ‘ ๐ธ๐‘— = ๐ธ , ๐ธ ๐‘› ๐‘—=1 โˆˆ [โˆ‘ ๐ธ๐‘— ๐‘› ๐‘—=1 (๐‘€๐‘†๐‘‡), โˆ‘ ๐ธ๐‘—(๐ธ๐ท๐ท)] ๐‘› ๐‘—=1 } . . . (๐‘†โ‚ฑ4). Given that ๐‘‡๐‘š๐‘Ž๐‘ฅ is a more important function in this problem Sโ‚ฑ4and should be perfect, the algorithm ๐‘บ๐‘ช๐‘บ๐‘ฌ๐‘ป๐Ÿ offers the best solution. IHJPAS. 37 (1) 2024 392 (5) 1//๐‘ณ๐’†๐’™(โˆ‘๐‘ฌ๐’‹, โˆ‘๐‘ช๐’‹, ๐‘ป๐’Ž๐’‚๐’™) (๐‘บโ‚ฑ5): This problem is defined as follows: ๐‘€๐‘–๐‘› {๐‘‡๐‘š๐‘Ž๐‘ฅ } s. t. โˆ‘ ๐ธ๐‘— = ๐ธ โˆ— where ๐ธโˆ— = โˆ‘ ๐ธ๐‘— ๐‘› ๐‘—=1 (๐‘€๐‘†๐‘‡) ๐‘› ๐‘—=1 โˆ‘ ๐ถ๐‘— ๐‘› ๐‘—=1 โ‰ค ๐ถ , ๐ถ โˆˆ [โˆ‘ ๐ถ๐‘—(๐‘†๐‘ƒ๐‘‡) ๐‘› ๐‘—=1 , โˆ‘ ๐ถ๐‘— ๐‘› ๐‘—=1 (๐‘€๐‘†๐‘‡)] } . . . (๐‘†โ‚ฑ5) . (6) 1//๐‘ณ๐’†๐’™(โˆ‘๐‘ฌ๐’‹, ๐‘ป๐’Ž๐’‚๐’™, โˆ‘๐‘ช๐’‹)(๐‘บโ‚ฑ6): The case can be written as: ๐‘€๐‘–๐‘› {โˆ‘ ๐ถ๐‘— ๐‘› ๐‘—=1 } s. t. โˆ‘ ๐ธ๐‘— ๐‘› ๐‘—=1 = ๐ธโˆ— where ๐ธโˆ— = ๐‘š๐‘–๐‘›{โˆ‘ ๐ธ๐‘— ๐‘› ๐‘—=1 (๐‘€๐‘†๐‘‡)} ๐‘‡๐‘š๐‘Ž๐‘ฅ โ‰ค ๐‘‡ , ๐‘‡ โˆˆ [๐‘‡๐‘š๐‘Ž๐‘ฅ(๐‘€๐‘†๐‘‡), ๐‘‡๐‘š๐‘Ž๐‘ฅ(๐ธ๐ท๐ท)] } . . . (๐‘†โ‚ฑ6). Given that 1// โˆ‘๐ธ๐‘— is an NP-hard problem, the problems (Sโ‚ฑ5) and (Sโ‚ฑ6) are both NP-hard. (7) 1// โˆ‘๐‘ช๐’‹ + โˆ‘๐‘ฌ๐’‹ + ๐‘ป๐’Ž๐’‚๐’™ ๐๐ซ๐จ๐›๐ฅ๐ž๐ฆ. The objective of the problem is to find the sequence of job processing that will minimize โˆ‘๐ถ๐‘— + โˆ‘๐ธ๐‘— + ๐‘‡๐‘š๐‘Ž๐‘ฅ . Following is a definition of this sub-problem: Suppose that ฮฑ is any machine schedule that is possible to formulate as follows for a given schedule ๐›ผ = (๐›ผ1, ๐›ผ2, โ€ฆ , ๐›ผ๐‘›). Assume that ฮฑ is any schedule that can be expressed as follows for a certain schedule ๐›ผ = (๐›ผ1, ๐›ผ2, โ€ฆ , ๐›ผ๐‘›): ๐น1 = ๐‘€๐‘–๐‘›{โˆ‘๐ถ๐‘— + โˆ‘๐ธ๐‘— + ๐‘‡๐‘š๐‘Ž๐‘ฅ} s. t. ๐ถ1 = ๐‘๐›ผ1 ๐ถ๐‘— โ‰ฅ ๐‘๐›ผ๐‘— ๐‘— = 1,2, โ€ฆ . , ๐‘› ๐ถ๐‘— = ๐ถ๐›ผ(๐‘—โˆ’1) + ๐‘๐›ผ๐‘— ๐‘— = 2,โ€ฆ . , ๐‘› ๐‘‡๐‘— โ‰ฅ ๐ถ๐‘— โˆ’ ๐‘‘๐›ผ๐‘— ๐‘— = 1,2, โ€ฆ . , ๐‘› ๐ธ๐‘— โ‰ฅ ๐‘‘๐›ผ๐‘— โˆ’ ๐ถ๐‘— ๐‘— = 1,2, โ€ฆ . , ๐‘› ๐‘‡๐‘— โ‰ฅ 0, ๐ธ๐‘— โ‰ฅ 0 ๐‘— = 1,2, โ€ฆ . , ๐‘› } โ€ฆ(Sโ‚ฑ7). Finding a processing order ๐›ผ = (๐›ผ1, โ€ฆ , ๐›ผ๐‘›) for the jobs on a single machine that minimizes the sum of the total completion times, the total earliness, and the maximum tardiness (โˆ‘๐ถ๐‘—(๐›ผ) + โˆ‘๐ธ๐‘—(๐›ผ) + ๐‘‡๐‘š๐‘Ž๐‘ฅ(๐›ผ)) , ๐›ผ โˆˆ ๐’ฎ (where ๐’ฎ is the set of all feasible solutions), is the aim of this problem. Proposition(2): The optimal solution for 1// โˆ‘๐ถ๐‘— + โˆ‘๐ธ๐‘— + ๐‘‡๐‘š๐‘Ž๐‘ฅ problem is an EFSO for the 1// ๐น(โˆ‘๐ถ๐‘— , โˆ‘๐ธ๐‘— , ๐‘‡๐‘š๐‘Ž๐‘ฅ). Proof: let ๐›ฝ be an optimal schedule for 1// โˆ‘๐ถ๐‘— + โˆ‘๐ธ๐‘— + ๐‘‡๐‘š๐‘Ž๐‘ฅ problem. Suppose that ๐›ฝ gives no efficient solution for the problem 1// ๐น(โˆ‘๐ถ๐‘— , โˆ‘๐ธ๐‘— , ๐‘‡๐‘š๐‘Ž๐‘ฅ), so there is a schedule ฮฑ which is efficient for 1// ๐น(โˆ‘๐ถ๐‘— , โˆ‘๐ธ๐‘— , ๐‘‡๐‘š๐‘Ž๐‘ฅ) problem such that: โˆ‘๐ถ๐‘— (๐›ผ) โ‰ค โˆ‘๐ถ๐‘—(๐›ฝ) and โˆ‘๐ธ๐‘— (๐›ผ) โ‰ค โˆ‘๐ธ๐‘—(๐›ฝ) and ๐‘‡๐‘š๐‘Ž๐‘ฅ(๐›ผ) โ‰ค ๐‘‡๐‘š๐‘Ž๐‘ฅ(๐›ฝ), and when there are strict inequities in at least one. As a result, it follows: IHJPAS. 37 (1) 2024 393 โˆ‘๐ถ๐‘— (๐›ผ) + โˆ‘๐ธ๐‘— (๐›ผ) + ๐‘‡๐‘š๐‘Ž๐‘ฅ(๐›ผ) โ‰ค โˆ‘๐ถ๐‘—(๐›ฝ) + โˆ‘๐ธ๐‘—(๐›ฝ) + ๐‘‡๐‘š๐‘Ž๐‘ฅ(๐›ฝ), so, for1// โˆ‘๐ถ๐‘— + โˆ‘๐ธ๐‘— + ๐‘‡๐‘š๐‘Ž๐‘ฅ , ๐›ผ is a schedule that gives the better solution from ๐›ฝ. However, since ๐›ฝis the optimal schedule, the assumption is contradicted, so ๐›ฝ should give an efficient solution to 1// โˆ‘๐ถ๐‘— + โˆ‘๐ธ๐‘— + ๐‘‡๐‘š๐‘Ž๐‘ฅ . 4. Special cases of the problems (๐‘บ๐‘ช๐‘บ๐‘ฌ๐‘ป)and (๐‘บโ‚ฑ๐Ÿ•) In this part, give some special cases and examples for problems (๐‘บ๐‘ช๐‘บ๐‘ฌ๐‘ป)and (๐‘บโ‚ฑ๐Ÿ•) that lead to efficient and optimal solutions respectively. 4.1 Special Cases of the Problem(๐‘บ๐‘ช๐‘บ๐‘ฌ๐‘ป) Case(๐Ÿ’. ๐Ÿ. ๐Ÿ): If ๐‘1 = ๐‘‘1and ๐‘๐‘— = ๐‘‘๐‘— โˆ’ ๐‘‘๐‘—โˆ’1, for all ๐‘— in ๐›ผ (except 1) then SPT schedule ๐›ผ gives an efficient schedule for problem (๐‘†๐ถ๐‘†๐ธ๐‘‡). Proof: Since ๐‘1 = ๐‘‘1 and ๐‘2 = ๐‘‘2 โˆ’ ๐‘‘1 = ๐‘‘2 โˆ’ ๐‘1, then ๐ถ1 = ๐‘‘1 and ๐ถ2 = ๐‘1 + ๐‘2 = ๐‘1 + ๐‘‘2 โˆ’ ๐‘1 = ๐‘‘2 then ๐ถ2 = ๐‘‘2 and so on ๐ถ๐‘— = ๐‘‘๐‘— for ๐‘— = 1,2, . . , ๐‘›. Since ๐ถ๐‘— = ๐‘‘๐‘— for all ๐‘— in ๐œŽ hence ๐ฟ๐‘— = 0 , โˆ€๐‘—, then ๐ธ๐‘— = ๐‘‡๐‘— = 0, so โˆ‘๐ธ๐‘— = ๐‘‡๐‘š๐‘Ž๐‘ฅ = 0. Then the problem 1 // (โˆ‘๐ถ๐‘— , โˆ‘๐ธ๐‘— , ๐‘‡๐‘š๐‘Ž๐‘ฅ) reduced to1 // โˆ‘๐ถ๐‘—. But the rule that solved this problem was SPT. Then ๐›ผ provides an efficient solution to (๐‘†๐ถ๐‘†๐ธ๐‘‡) problem . Case(๐Ÿ’. ๐Ÿ. ๐Ÿ): If ๐‘๐‘— = ๐‘ and ๐‘‘๐‘— = ๐‘—๐‘ for all ๐‘— in the schedule ฯƒ,then ๐œŽ gives an EFSO to (๐‘†๐ถ๐‘†๐ธ๐‘‡). Proof: Since ๐‘‘๐‘— = ๐‘—๐‘ = ๐ถ๐‘— โˆ€๐‘— โˆˆ ๐œŽ, (this means there is no job late and early s. t. ๐ธ๐‘— = 0 = ๐‘‡๐‘—) then โˆ‘ ๐ธ๐‘— = ๐‘‡๐‘š๐‘Ž๐‘ฅ = 0๐‘› ๐‘—=1 . Then the problem 1// ๐น(โˆ‘๐ถ๐‘— , โˆ‘๐ธ๐‘— , ๐‘‡๐‘š๐‘Ž๐‘ฅ) reduced to 1// โˆ‘ ๐ถ๐‘— ๐‘› ๐‘—=1 . Now since ๐‘๐‘— = ๐‘ for every job ๐‘— in ฮฑ, then โˆ‘ ๐ถ๐‘— ๐‘› ๐‘—=1 = ๐‘ ( ๐‘›2+๐‘› 2 ). But ๐‘ ( ๐‘›2+๐‘› 2 ) is constant, hence any schedule gives an EFSO to (๐‘†๐ถ๐‘†๐ธ๐‘‡). As a result, every schedule provides an efficient solution to the problem. Case (๐Ÿ’. ๐Ÿ. ๐Ÿ‘): If ๐‘‘๐‘— = ๐‘˜๐‘๐‘— for all ๐‘˜ โ‰ฅ 2 and ๐‘— โˆˆ ฮฑ = SPT schedule then ๐›ผ is an EFSO to the (๐‘†๐ถ๐‘†๐ธ๐‘‡). proof: Let ๐‘ ๐‘— = ๐‘‘๐‘— โˆ’ ๐‘๐‘— be the slack time of the job j (๐‘— = 1,โ€ฆ , ๐‘›) since ๐‘‘๐‘— = ๐‘˜๐‘๐‘— then ๐‘ ๐‘— = ๐‘˜๐‘๐‘— โˆ’ ๐‘๐‘— = (๐‘˜ โˆ’ 1)๐‘๐‘—. Since SPT schedule, the processing time for tasks is arranged in a non- descending sequence (this meam ๐‘๐‘– โ‰ค ๐‘๐‘— for all ๐‘– โ‰ค ๐‘—). Then (๐‘˜ โˆ’ 1)๐‘1 โ‰ค (๐‘˜ โˆ’ 1)๐‘2 โ‰ค โ‹ฏ โ‰ค (๐‘˜ โˆ’ 1)๐‘๐‘›, hence ๐‘ 1 โ‰ค ๐‘ 2 โ‰ค โ‹ฏ โ‰ค ๐‘ ๐‘›. which is MST order, since MST order gives EFSO for โˆ‘๐ธ๐‘—. Hence SPT is efficient for (๐‘†๐ถ๐‘†๐ธ๐‘‡). Case(๐Ÿ’. ๐Ÿ. ๐Ÿ’): If SPT and MST are identical then they give an efficient schedule for (๐‘†๐ถ๐‘†๐ธ๐‘‡). Proof: Since SPT and MST are identical then โˆ‘ ๐ถ๐‘— ๐‘› ๐‘—=1 is minimum value, and โˆ‘๐ธ๐‘— is minimum value. But ๐‘ ๐‘— = ๐‘‘๐‘— โˆ’ ๐‘๐‘— and ๐‘‘1 โˆ’ ๐‘1 โ‰ค. . . โ‰ค ๐‘‘๐‘› โˆ’ ๐‘๐‘› then ๐‘‘1 โˆ’ ๐‘1 + ๐‘1 โ‰ค. . . โ‰ค ๐‘‘๐‘› โˆ’ ๐‘๐‘› + ๐‘๐‘› (since ๐‘1 โ‰ค โ‹ฏ โ‰ค ๐‘๐‘›), hence ๐‘‘1 โ‰ค. . . โ‰ค ๐‘‘๐‘›(which is EDD order), since the EDD order gives EFSO for the ๐‘‡๐‘— then ๐‘‡๐‘š๐‘Ž๐‘ฅ is minimum. Hence all schedule an EFSO for (๐‘†๐ถ๐‘†๐ธ๐‘‡) . Case(๐Ÿ’. ๐Ÿ. ๐Ÿ“): If the processing times of all jobs are identical, then MST ordered is EFSO to problem (๐‘†๐ถ๐‘†๐ธ๐‘‡). IHJPAS. 37 (1) 2024 394 Proof: Since the processing times of all jobs are identical, then โˆ‘๐ถ๐‘— = ๐‘ ( ๐‘›(๐‘›+1) 2 ), it is the same for any sequence. Since MST schedule, ordered the slack time of jobs in a non-decreasing sequence (that mean ๐‘ ๐‘– โ‰ค ๐‘ ๐‘— for all ๐‘– โ‰ค ๐‘— in MST schedule). Since ๐‘ ๐‘— = ๐‘‘๐‘— โˆ’ ๐‘, using MST rule and adding ๐‘ for each term, is produced ๐‘‘๐‘– โ‰ค ๐‘‘๐‘— for all ๐‘– โ‰ค ๐‘— (which is EDD order), hence EDD and MST are identical. Since MST order gives efficient value for โˆ‘๐ธ๐‘— and EDD order gives efficient value for the ๐‘‡๐‘— then ๐‘‡๐‘š๐‘Ž๐‘ฅ is minimum. Hence MST is an EFSO for the third criterion โˆ‘๐ถ๐‘—, โˆ‘๐ธ๐‘—, ๐‘‡๐‘š๐‘Ž๐‘ฅ . Case(๐Ÿ’. ๐Ÿ. ๐Ÿ”): If ๐‘‘๐‘— = ๐‘‘, and SPT and MST are identical โˆ€๐‘—, (๐‘— = 1,2, . . . , ๐‘›) in a schedule ฮฑ, then ๐›ผ is EFSO to ( ๐‘†๐ถ๐‘†๐ธ๐‘‡ ). Proof: Since ๐‘‘๐‘— = ๐‘‘ , there are two cases: a) If ๐‘‘๐‘— = ๐‘‘ = ๐‘๐‘—, hence ๐ถ๐‘— โ‰ฅ ๐‘‘๐‘— for all ๐‘— (this means all jobs are late s. t. ๐ธ๐‘— = 0 = โˆ‘๐ธ๐‘— for all ๐‘—). Then 1// (โˆ‘๐ถ๐‘— , โˆ‘๐ธ๐‘— , ๐‘‡๐‘š๐‘Ž๐‘ฅ) reduce to 1// (โˆ‘๐ถ๐‘—, ๐‘‡๐‘š๐‘Ž๐‘ฅ), as result, the SPT rule provides an EFSO to the problem ( ๐‘†๐ถ๐‘†๐ธ๐‘‡ ).where ๐‘‘๐‘— = ๐‘‘ for all the orders of ๐‘— and SPT gives EFSO for 1// โˆ‘๐ถ๐‘—. b) ๐‘‘๐‘— = ๐‘‘ > ๐‘๐‘— for all ๐‘— hence either ๐‘‘ โ‰ค ๐ถ๐‘— or ๐ถ๐‘— > ๐‘‘, since SPT and MST are identical (this mean โˆ‘๐ถ๐‘— , โˆ‘๐ธ๐‘— is minimum values). Then a schedule ๐›ผ is an EFSO to ( ๐‘†๐ถ๐‘†๐ธ๐‘‡ ). Case (๐Ÿ’. ๐Ÿ. ๐Ÿ•): if ๐‘๐‘— = ๐‘, ๐‘‘๐‘— = ๐‘‘ and ๐‘‘ โ‰ค ๐ถ๐‘— for all ๐‘— in a schedule ฮฑ then any schedule ๐›ผ is EFSO to ( ๐‘†๐ถ๐‘†๐ธ๐‘‡ ). Proof: Since ๐‘‘ โ‰ค ๐ถ๐‘— for all ๐‘— (this means all jobs are late s. t. ๐ธ๐‘— = 0 = โˆ‘๐ธ๐‘— ) and ๐‘‡๐‘— = ๐‘š๐‘Ž๐‘ฅ{๐ฟ๐‘— , 0} = ๐‘š๐‘Ž๐‘ฅ{๐‘—๐‘ โˆ’ ๐‘‘, 0} then ๐‘‡๐‘š๐‘Ž๐‘ฅ = ๐‘š๐‘Ž๐‘ฅ{๐‘š๐‘Ž๐‘ฅ{๐‘—๐‘ โˆ’ ๐‘‘, 0}} = ๐‘›๐‘ โˆ’ ๐‘‘. Hence 1 โˆ•โˆ• (โˆ‘๐ถ๐‘— , โˆ‘ ๐ธ๐‘— , ๐‘‡๐‘š๐‘Ž๐‘ฅ) reduced to 1// (โˆ‘๐ถ๐‘— , ๐‘‡๐‘š๐‘Ž๐‘ฅ) = (๐‘ ( ๐‘›2+๐‘› 2 ) , ๐‘›๐‘ โˆ’ ๐‘‘). Then any schedule is an EFSO to (๐‘†๐ถ๐‘†๐ธ๐‘‡) because the three quantities are constant. Case(๐Ÿ’. ๐Ÿ. ๐Ÿ–): If ๐‘‘๐›ผ๐‘– + ๐‘๐›ผ๐‘— โ‰ค ๐‘‘๐›ผ๐‘— for all ๐‘–, ๐‘— in ๐‘†๐‘ƒ๐‘‡ schedule ๐›ผ , where ๐‘– โ‰ค ๐‘—, SPT and EDD are identical, then ๐›ผ is the EFSO for (๐‘†๐ถ๐‘†๐ธ๐‘‡). Proof: Since ๐‘‘๐›ผ๐‘– + ๐‘๐›ผ๐‘— โ‰ค ๐‘‘๐›ผ๐‘— โˆ€๐‘–, ๐‘— in ๐›ผ, then ๐‘‘๐›ผ๐‘– โ‰ค ๐‘‘๐›ผ๐‘— โˆ’ ๐‘๐›ผ๐‘— for all ๐‘–, ๐‘— and ๐‘‘๐›ผ๐‘– โˆ’ ๐‘๐›ผ๐‘– โ‰ค ๐‘‘๐›ผ๐‘— โˆ’ ๐‘๐›ผ๐‘— , for all ๐‘–, ๐‘— (Since ๐‘๐›ผ๐‘– โ‰ฅ 0 and ๐‘๐›ผ๐‘– โ‰ค ๐‘๐›ผ๐‘— ).Then s๐›ผ๐‘– โ‰ค s๐›ผ๐‘— , for all ๐‘–, ๐‘— (this mean all jobs are ordered in MST order for all ๐‘–, ๐‘— in ๐›ผ), then โˆ‘๐ธ๐‘— is minimum. Hence SPT gives the optimal solution for both criteria โˆ‘๐ธ๐‘— ๐‘Ž๐‘›๐‘‘ โˆ‘๐ถ๐‘—, and ๐‘‡๐‘š๐‘Ž๐‘ฅ(SPT) = ๐‘‡๐‘š๐‘Ž๐‘ฅ(๐ธ๐ท๐ท) (since SPT and EDD are identical). Then SPT is an EFSO for the problem (๐‘†๐ถ๐‘†๐ธ๐‘‡) . Case(๐Ÿ’. ๐Ÿ. ๐Ÿ—): If ๐‘‘๐‘— + ๐‘๐‘— โ‰ค ๐ถ๐‘—+1 for ๐‘— = 1,2, . . , ๐‘› โˆ’ 1 then the SPT schedule is an EFSO for (๐‘†๐ถ๐‘†๐ธ๐‘‡) . Proof: Let ๐œŽ = (๐œŽ1, ๐œŽ2, . . , ๐œŽ๐‘›) by SPT sequence, since ๐‘‘๐‘— + ๐‘๐‘— โ‰ค ๐ถ๐‘—+1 , โˆ€๐‘—(๐‘— = 1,2, . . , ๐‘› โˆ’ 1). Then ๐‘‘๐‘— โ‰ค ๐ถ๐‘—+1 โˆ’ ๐‘๐‘— = โˆ‘ ๐‘๐‘– ๐‘—+1 ๐‘–=1 โˆ’ ๐‘๐‘— = ๐ถ๐‘— + ๐‘๐‘—+1 โˆ’ ๐‘๐‘— โˆ€๐‘—(๐‘— = 1,2, . . , ๐‘› โˆ’ 1). ๐ถ๐‘— + ๐‘๐‘—+1 โˆ’ ๐‘๐‘— = { ๐ถ๐‘— if ๐‘๐‘— = ๐‘๐‘—+1 , ๐‘— = 1,2, . . , ๐‘› โˆ’ 1 ๐ถ๐‘— + ๐‘ if ๐‘ = ๐‘๐‘—+1 โˆ’ ๐‘๐‘— , ๐‘— = 1,2, . . , ๐‘› โˆ’ 1 } (1) Since ๐œŽ is the SPT schedule, there are two cases: IHJPAS. 37 (1) 2024 395 a) ๐‘๐‘— = ๐‘๐‘—+1, for ๐‘— = 1,2, . . , ๐‘› โˆ’ 1 and Equation (1). Hence ๐‘‘๐‘— โ‰ค ๐ถ๐‘— (this means all jobs are late s. t. ๐ธ๐‘— = 0 = โˆ‘๐ธ๐‘—). The problem 1 โˆ•โˆ• (โˆ‘๐ถ๐‘— , โˆ‘ ๐ธ๐‘— , ๐‘‡๐‘š๐‘Ž๐‘ฅ) reduced to 1// (โˆ‘๐ถ๐‘— , ๐‘‡๐‘š๐‘Ž๐‘ฅ), so SPT schedule is an EFSO . b) ๐‘๐‘— < ๐‘๐‘—+1, for ๐‘— = 1,2, . . , ๐‘› โˆ’ 1 and by (4.1),then ๐‘‘๐‘— โ‰ค ๐ถ๐‘— + ๐‘, ๐‘ > 0 then ๐‘‘๐‘— โˆ’ ๐ถ๐‘— โ‰ค ๐‘ (this means all jobs are late ๐‘ . ๐‘ก. ๐ธ๐‘— = 0 = โˆ‘๐ธ๐‘—), hence 1 โˆ•โˆ• (โˆ‘๐ถ๐‘— , โˆ‘ ๐ธ๐‘— , ๐‘‡๐‘š๐‘Ž๐‘ฅ)reduced to 1// (โˆ‘๐ถ๐‘— , ๐‘‡๐‘š๐‘Ž๐‘ฅ), also SPT rule is an EFSO . Case(๐Ÿ’. ๐Ÿ. ๐Ÿ๐ŸŽ): If ๐ถ๐‘— โ‰ฅ ๐‘‘๐‘— and SPT, EDD rules are identical for all ๐‘— in a schedule ๐›ผ, then ๐›ผ schedule gives an EFSO for (๐‘†๐ถ๐‘†๐ธ๐‘‡). Proof: Let ฯƒ be an SPT schedule with ๐ถ๐‘— โ‰ฅ ๐‘‘๐›ผ๐‘— for each ๐‘— in ๐œŽ (this means that all jobs in the SPT schedule are late), hence ๐ธ๐‘— = 0 = โˆ‘๐ธ๐‘— for all ๐‘— in ๐›ผ. then 1// ๐น(โˆ‘๐ถ๐‘— , โˆ‘ ๐ธ๐‘— , ๐‘‡๐‘š๐‘Ž๐‘ฅ) reduced to 1//(โˆ‘๐ถ๐‘— , ๐‘‡๐‘š๐‘Ž๐‘ฅ).Hence SPT schedule is efficient for (๐‘†๐ถ๐‘†๐ธ๐‘‡) . Case(4.1.11): If the SPT schedule gives ๐ถ๐‘— โ‰ค ๐‘‘๐‘— โˆ€๐‘– โˆˆ ๐‘ then this SPT schedule gives an EFSO for (๐‘†๐ถ๐‘†๐ธ๐‘‡). Proof: Since ๐ถ๐‘— โ‰ค ๐‘‘๐‘— for all ๐‘— in the SPT schedule (this means all jobs are early s. t. ๐‘‡๐‘— = 0 = ๐‘‡๐‘š๐‘Ž๐‘ฅ for all ๐‘—) and ๐ธ๐‘— = ๐‘š๐‘Ž๐‘ฅ{โˆ’๐ฟ๐‘— , 0} then โˆ‘๐ธ๐‘— = โˆ‘๐‘š๐‘Ž๐‘ฅ{โˆ’๐ฟ๐‘— , 0} for all ๐‘—. Hence 1// ๐น(โˆ‘๐ถ๐‘— , โˆ‘๐ธ๐‘— , ๐‘‡๐‘š๐‘Ž๐‘ฅ) reduced to 1// (โˆ‘๐ถ๐‘—, โˆ‘ ๐ธ๐‘—). Hence SPT rule gives an EFSO. 4.2 Special Cases for Subproblem (Sโ‚ฑ7) We introduce some special cases for the problem (Sโ‚ฑ7)that has optimal solutions in this section. Case(4.2.1): If ๐‘1 = ๐‘‘1and ๐‘๐‘— = ๐‘‘๐‘— โˆ’ ๐‘‘๐‘—โˆ’1, for all ๐‘— in ๐›ผ (except 1) then SPT schedule ๐›ผ gives an optimal solution for the problem 1// โˆ‘๐ถ๐‘— + โˆ‘๐ธ๐‘— + ๐‘‡๐‘š๐‘Ž๐‘ฅ. Proof: Proof as in case (4.1.1) and (โˆ‘๐ถ๐‘— + โˆ‘๐ธ๐‘— + ๐‘‡๐‘š๐‘Ž๐‘ฅ)=โˆ‘๐ถ๐‘—. Case(4.2.2): If ๐‘๐‘— = ๐‘ and ๐‘‘๐‘— = ๐‘—๐‘ for all ๐‘— in the schedule ฯƒ, then ๐œŽ gives an optimal solution for the problem 1// (โˆ‘๐ถ๐‘— + โˆ‘๐ธ๐‘— + ๐‘‡๐‘š๐‘Ž๐‘ฅ). Proof: Verified by the case (4.1.2), hence (โˆ‘๐ถ๐‘— + โˆ‘๐ธ๐‘— + ๐‘‡๐‘š๐‘Ž๐‘ฅ) = โˆ‘ ๐ถ๐‘— ๐“ƒ ๐‘—=1 = ๐‘ ( ๐‘›2+๐‘› 2 ) . Case (4.2.3): If ๐‘‘๐‘— = ๐‘˜๐‘๐‘— for all ๐‘˜ โ‰ฅ 2 then the SPT schedule is an optimal solution for the problem (Sโ‚ฑ7). Proof: Proof as in case (4.1.3). Case (4.2.4): If SPT and MST are identical then they give an optimal schedule for the problem (Sโ‚ฑ7). Proof: Proof as in case (4.1.4). Case (4.2.5): If ๐‘๐‘— = ๐‘ โˆ€๐‘— โˆˆ ๐‘, then the EDD schedule is an optimal schedule for (Sโ‚ฑ7). Proof: Proof as in case (4.1.5). Case(4.2.6): If ๐‘‘๐‘— = ๐‘‘, and SPT and MST are identical โˆ€๐‘—, (๐‘— = 1,2, โ€ฆ , ๐‘›) in schedule ๐›ผ then the ๐›ผ gives an optimal value for (Sโ‚ฑ7). Proof: Proof as in case (4.1.6), and IHJPAS. 37 (1) 2024 396 โˆ‘ ๐ถ๐‘— ๐‘› ๐‘—=1 + โˆ‘ ๐ธ๐‘— ๐‘› ๐‘—=1 + ๐‘‡๐‘š๐‘Ž๐‘ฅ = { โˆ‘ ๐ถ๐‘— ๐‘› ๐‘—=1 + ๐‘‡๐‘š๐‘Ž๐‘ฅ, , if ๐‘‘ = ๐‘๐‘—(๐‘–. ๐‘’. , ๐ถ๐‘— โ‰ฅ ๐‘‘๐‘— = ๐‘‘) โˆ‘ ๐ถ๐‘— ๐‘› ๐‘—=1 + โˆ‘ ๐ธ๐‘— ๐‘› ๐‘—=1 + ๐‘‡๐‘š๐‘Ž๐‘ฅ = โˆ‘ ๐‘‘๐‘› ๐‘—=1 + ๐‘‡๐‘š๐‘Ž๐‘ฅ, if ๐‘‘ > ๐‘๐‘— then either ๐ถ๐‘— โ‰ฅ ๐‘‘๐‘— or ๐ถ๐‘— < ๐‘‘๐‘— . Case (4.2.7): Any schedule gives an optimal solution for the problem Sโ‚ฑ7 if ๐‘๐‘— = ๐‘, ๐‘‘๐‘— = ๐‘‘ and ๐‘‘ โ‰ค ๐ถ๐‘— โˆ€๐‘—(๐‘— = 1,2, โ€ฆ . , ๐‘›). Proof: Proof as in case (4.1.7), and (โˆ‘๐ถ๐‘— + โˆ‘๐ธ๐‘— + ๐‘‡๐‘š๐‘Ž๐‘ฅ) = ๐‘ ( ๐‘›2+๐‘› 2 ) + ๐‘›๐‘ โˆ’ ๐‘‘ . If ๐‘‘๐›ผ๐‘– + ๐‘๐›ผ๐‘— โ‰ค ๐‘‘๐›ผ๐‘— for all ๐‘–, ๐‘— in schedule ๐‘†๐‘ƒ๐‘‡ ๐›ผ , where ๐‘– โ‰ค ๐‘— and SPT and EDD are identical, then ๐›ผ is the EFSO for (๐‘†๐ถ๐‘†๐ธ๐‘‡). Case (4.2.8): If ๐‘‘๐›ผ๐‘– + ๐‘๐›ผ๐‘— โ‰ค ๐‘‘๐›ผ๐‘— for all ๐‘–, ๐‘— in schedule ๐‘†๐‘ƒ๐‘‡ ๐›ผ , where ๐‘– โ‰ค ๐‘— , SPT and EDD are identical, then ๐›ผ is the optimal solution for (Sโ‚ฑ7). Proof: Proof as in case (4.1.8). Case (4.2.9): If ๐‘‘๐‘— + ๐‘๐‘— โ‰ค ๐ถ๐‘—+1 for ๐‘— = 1,2, . . , ๐‘› โˆ’ 1 then the SPT schedule is an optimal solution for (๐‘†โ‚ฑ7). Proof: Verified by the case (4.1.9). Case (4.2.10): If ๐ถ๐‘— โ‰ฅ ๐‘‘๐‘— , SPT and EDD rules are identical for all ๐‘— in a schedule ๐›ผ, then schedule ๐›ผ gives an optmal solution for(๐‘†โ‚ฑ7). Proof: Verified by the case (4.1.10). Case (4.2.11): If the SPT schedule gives ๐ถ๐‘— โ‰ค ๐‘‘๐‘— โˆ€๐‘– โˆˆ ๐‘ then this SPT schedule gives an optimal schedule for (๐‘†โ‚ฑ7). Proof: Proof as in case (4.1.11). In Table 3, an examples give for describing the special cases for two problems ( ๐‘†๐ถ๐‘†๐ธ๐‘‡ ) and (๐‘†โ‚ฑ7) by calculating the objective functions(๐น)and (๐น1)respectively, using 6 jobs. IHJPAS. 37 (1) 2024 397 Table 3. Special Cases of Problem ( ๐‘†๐ถ๐‘†๐ธ๐‘‡ ) and (๐‘†โ‚ฑ7) In the following examples. 5. Dominance Rules for Single Machine Scheduling Problem Dominance Rules (DRs) are used efficiently in reducing the current sequences[23-25]. DR is used usually to indicate whether a certain node in a BAB method can be eliminated before calculating its lower bound. These rules are been useful when a node has a lower bound less than the optimum solution and can be eliminated [26-28]. When the nodes are dominated by others in the BAB procedure, DRs can be used also to cut these nodes. Such developments may heavily reduce the number of nodes in searching for an efficient solution. Where the DRs are also applicable to such problems[29,30]. The dominance rules as we mentioned before are used in an attempt to eliminate nodes in the BAB method which makes us reduce the time spent on solving this problem1// โˆ‘๐ถ๐‘— + โˆ‘๐ธ๐‘— + ๐‘‡๐‘š๐‘Ž๐‘ฅ . Rule (1): If ๐‘๐‘– โ‰ค ๐‘๐‘— and ๐‘‘๐‘– โ‰ค ๐‘‘๐‘— then there is an optimal schedule wherein the job ๐‘– processing before job . Proof: Consider a schedule ๐œŽ = ๐œŽ1๐‘–๐‘—๐œŽ2 and a schedule ๏ฟฝฬ‡๏ฟฝ = ๐œŽ1๐‘—๐‘–๐œŽ2 see Figure (1) Figure1. The scheduling ๐œŽ and๏ฟฝฬˆ๏ฟฝ ๐น1 ๐น conditions ๐’‘๐’‹ ๐š๐ง๐ ๐’…๐’‹ case 57 (57,0,0) ๐‘1 = ๐‘‘1and ๐‘๐‘— = ๐‘‘๐‘— โˆ’ ๐‘‘๐‘—โˆ’1 for all ๐‘— ๐‘๐‘— = 1,2,4,7,5,3 , ๐‘‘๐‘— = 1,3,10,22,22,15,6 (4.1.1) (4.2.1) 126 (126,0,0) ๐‘๐‘— = ๐‘ and ๐‘‘๐‘— = ๐‘—๐‘ , โˆ€๐‘— ๐‘๐‘— = 6, ๐‘‘๐‘— = 6,12,18,24,30,36 (4.1.2) (4.2.2) 94 (78,12,4) ๐‘‘๐‘— = ๐‘˜๐‘๐‘— for all ๐‘˜ โ‰ฅ 2 ๐‘๐‘— = 3,4,2,5,6,8 , ๐‘‘๐‘— = 9,12,6,15,18,24 (4.1.3) (42.3) 267 (222,2,43) ๐‘๐‘– โ‰ค ๐‘๐‘— and ๐‘ ๐‘– โ‰ค ๐‘ ๐‘— for all ๐‘— . ๐‘๐‘— = 6,10,12,14,14,18 , ๐‘ ๐‘— = 2,4,8,10,12,13. (4.1.4) (4.2.4) 72 (63,0,9) ๐‘๐‘— = ๐‘ for all ๐‘— in a schedule EDD ๐›ผ . ๐‘๐‘— = 3 , ๐‘‘๐‘— = 3,4,6,7,8,9 (4.1.5) (4.2.5) 62 (41,11,10) ๐‘‘๐‘— = ๐‘‘,โˆ€๐‘— ๐‘๐‘— = 5,4,3,2,1,1 , ๐‘‘๐‘— = 6 (4.1.6) (4.2.6) 123 (106,0,17) ๐‘๐‘— = 7,6,5,3,2,1 , ๐‘‘๐‘— = 7 130 (105,0,25) ๐‘๐‘— = ๐‘ , ๐‘‘๐‘— = ๐‘‘, ๐‘‘ โ‰ค ๐ถ๐‘—for all ๐‘— ๐‘ = ๐‘‘ = 5 (4.1.7) (4.2.7) 130 (105,2,23) ๐‘ = 5, ๐‘‘ = 7 , ๐‘ < ๐‘‘ 34 (34,0,0) ๐‘‘๐‘– + ๐‘๐‘— โ‰ค ๐‘‘๐‘— for all ๐‘— , SPT and EDD rules are identical. ๐‘๐‘— = 1,1,3,3,2,2 , ๐‘‘๐‘— = 1,2,9,12,4,6 (4.1.8) (4.2.8) 73 (59,0,14) ๐‘‘๐‘— + ๐‘๐‘— โ‰ค ๐ถ๐‘—+1 for all ๐‘— = 2,3, โ€ฆ , ๐‘› ๐‘๐‘— = 5,4,3,2,4,2 , ๐‘‘๐‘— = 6,7,4,3,5,2 (4.1.9) (4.2.9) 39 126 (35,0,4) (101,0,25) ๐ถ๐‘— โ‰ฅ ๐‘‘๐‘— , for all ๐‘— ๐‘๐‘— = 4,3,2,2,1,1 , ๐‘‘๐‘— = 14,9,5,6,2,3 ๐‘๐‘— = 3,4,5,6,8,9 , ๐‘‘๐‘— = 3,5,6,7,9,10 (4.1.10) (4.2.10) 83 (78,5,0) ๐ถ๐‘— โ‰ค ๐‘‘๐‘— , for all ๐‘— ๐‘๐‘— = 8,5,2,6,4,3, ๐‘‘๐‘— = 30,14,2,21,10,6 (4.1.11) (4.2.11) IHJPAS. 37 (1) 2024 398 which is obtained by interchanging the jobs i and j in ฯƒ. For these schedules, we study two cases, and in every case, we will make a comparison between them. First case: If ๐‘๐‘– โ‰ค ๐‘๐‘— , ๐‘‘๐‘– โ‰ค ๐‘‘๐‘— produces that ๐‘ ๐‘– โ‰ค ๐‘ ๐‘— In this situation, there are: The condition of the processing times ensures that: โˆ‘๐ถ๐’ฆ(๐œŽ) โ‰ค โˆ‘๐ถ๐’ฆ(๏ฟฝฬ‡๏ฟฝ) (2) And the condition of the slack times ensures that: ๐ธ๐‘š๐‘Ž๐‘ฅ(๐œŽ) โ‰ค ๐ธ๐‘š๐‘Ž๐‘ฅ(๏ฟฝฬ‡๏ฟฝ) then โˆ‘๐ธ๐’ฆ(๐œŽ) โ‰ค โˆ‘๐ธ๐’ฆ(๏ฟฝฬ‡๏ฟฝ) And the condition on the due date ensures that: ๐‘‡๐‘š๐‘Ž๐‘ฅ(๐œŽ) โ‰ค ๐‘‡๐‘š๐‘Ž๐‘ฅ(๏ฟฝฬ‡๏ฟฝ) (3) Hence โˆ‘๐ถ๐’ฆ(๐œŽ) + โˆ‘๐ธ๐’ฆ(๐œŽ) + ๐‘‡๐‘š๐‘Ž๐‘ฅ(๐œŽ) โ‰ค โˆ‘๐ถ๐’ฆ(๏ฟฝฬ‡๏ฟฝ) + โˆ‘๐ธ๐’ฆ(๏ฟฝฬ‡๏ฟฝ) + ๐‘‡๐‘š๐‘Ž๐‘ฅ(๏ฟฝฬ‡๏ฟฝ) Second case: If ๐‘๐‘– โ‰ค ๐‘๐‘— , ๐‘‘๐‘– โ‰ค ๐‘‘๐‘— yields that ๐‘ ๐‘– โ‰ฅ ๐‘ ๐‘— . In this situation, The condition on the processing times ensures that (5.1) is satisfied, and the cost which is obtained from Equation (2) is equal to ๐‘๐‘— โˆ’ ๐‘๐‘– i. e. โˆ‘๐ถ๐’ฆ(๏ฟฝฬ‡๏ฟฝ) = โˆ‘๐ถ๐’ฆ(๐œŽ) + ๐‘๐‘— โˆ’ ๐‘๐‘– (4) , then ๐‘‘๐‘– โˆ’ ๐ถ๐‘–(๐œŽ) = ๐‘‘๐‘– โˆ’ ๐ถ๐‘—(๏ฟฝฬ‡๏ฟฝ) + ๐‘๐‘— โˆ’ ๐‘๐‘–, since ๐ถ๐‘–(๐œŽ) = ๐ถ๐‘—(๏ฟฝฬ‡๏ฟฝ) โˆ’ ๐‘๐‘— + ๐‘๐‘– . since ๐‘ ๐‘– = ๐‘‘๐‘– โˆ’ ๐‘๐‘– โ‰ฅ ๐‘ ๐‘— = ๐‘‘๐‘— โˆ’ ๐‘๐‘— then ๐‘‘๐‘– โˆ’ ๐‘๐‘– โˆ’ ๐ถ๐‘—(๏ฟฝฬ‡๏ฟฝ) โ‰ฅ ๐‘‘๐‘— โˆ’ ๐‘๐‘— โˆ’ ๐ถ๐‘—(๏ฟฝฬ‡๏ฟฝ) hence ๐‘‘๐‘– โˆ’ ๐‘๐‘– + ๐‘๐‘— โˆ’ ๐ถ๐‘—(๏ฟฝฬ‡๏ฟฝ) โ‰ฅ ๐‘‘๐‘— โˆ’ ๐’ž๐‘—(๏ฟฝฬ‡๏ฟฝ) , from which we deduce that ๐ธ๐‘š๐‘Ž๐‘ฅ(๐œŽ) โ‰ฅ ๐ธ๐‘š๐‘Ž๐‘ฅ(๏ฟฝฬ‡๏ฟฝ) then โˆ‘๐ธ๐’ฆ(๐œŽ) โ‰ฅ โˆ‘๐ธ๐’ฆ(๏ฟฝฬ‡๏ฟฝ) the addition in cost which is obtained from this inequality is equal to ๐‘ ๐‘– โˆ’ ๐‘ ๐‘—, i.e., โˆ‘๐ธ๐’ฆ(๐œŽ) = โˆ‘๐ธ๐’ฆ(๏ฟฝฬ‡๏ฟฝ) + (๐‘ ๐‘– โˆ’ ๐‘ ๐‘—) (5). Since ๐‘๐‘– โ‰ค ๐‘๐‘— then ๐‘๐‘— โˆ’ ๐‘๐‘– โ‰ฅ 0 โˆ€๐‘–, ๐‘— Since ๐‘‘๐‘– โ‰ค ๐‘‘๐‘— then ๐‘‘๐‘— โˆ’ ๐‘‘๐‘– โ‰ฅ 0 โˆ€๐‘–, ๐‘— From ๐‘ ๐‘– โˆ’ ๐‘ ๐‘— โ‰ค ๐‘๐‘— โˆ’ ๐‘๐‘– , then โˆ‘๐ธ๐’ฆ(๏ฟฝฬ‡๏ฟฝ) + (๐‘ ๐‘– โˆ’ ๐‘ ๐‘—) โ‰ค โˆ‘๐ธ๐’ฆ(๏ฟฝฬ‡๏ฟฝ) + ๐‘๐‘— โˆ’ ๐‘๐‘– . (by adding โˆ‘๐ธ๐‘˜(๏ฟฝฬ‡๏ฟฝ) for both sides) by Equation (5) Then โˆ‘๐ถ๐’ฆ(๐œŽ) + โˆ‘๐ธ๐’ฆ(๐œŽ) โ‰ค โˆ‘๐ถ๐’ฆ(๐œŽ) + ๐‘๐‘— โˆ’ ๐‘๐‘– + โˆ‘๐ธ๐’ฆ(๏ฟฝฬ‡๏ฟฝ) . From Equation (3) โˆ‘๐ถ๐’ฆ(๐œŽ) + โˆ‘๐ธ๐’ฆ(๐œŽ) โ‰ค โˆ‘๐ถ๐’ฆ(๏ฟฝฬ‡๏ฟฝ) + โˆ‘๐ธ๐’ฆ(๏ฟฝฬ‡๏ฟฝ)(by adding ๐‘‡๐‘š๐‘Ž๐‘ฅ for both sides) . And โˆ‘๐ถ๐’ฆ(๐œŽ) + โˆ‘๐ธ๐’ฆ(๐œŽ) + ๐‘‡๐‘š๐‘Ž๐‘ฅ(๐œŽ) โ‰ค โˆ‘๐ถ๐’ฆ(๏ฟฝฬ‡๏ฟฝ) + โˆ‘๐ธ๐’ฆ(๏ฟฝฬ‡๏ฟฝ) + ๐‘‡๐‘š๐‘Ž๐‘ฅ(๏ฟฝฬ‡๏ฟฝ) . Rule (2): The schedule ฯƒij is dominated by the schedule ฯƒji if the following inequalities hold: (1) ๐‘๐‘– โ‰ค ๐‘๐‘— (2) ๐‘‘๐‘— โ‰ค ๐‘‘๐‘– (3) ๐‘‘๐‘— โ‰ฅ ๐‘ ๐‘–. Proof: Consider a schedule ๐œŽ = ๐œŽ1๐‘–๐‘—๐œŽ2 and a schedule ๏ฟฝฬ‡๏ฟฝ = ๐œŽ1๐‘—๐‘–๐œŽ2 which is obtained by interchanging the jobs i and j in ฯƒ. The condition of the processing times ensures that (โˆ‘C๐’ฆ(ฯƒ) โ‰ค โˆ‘C๐’ฆ(ฯƒฬ‡) is satisfied and then the addition in cost is obtained by ( โˆ‘๐ถ๐’ฆ(๏ฟฝฬ‡๏ฟฝ) = โˆ‘๐ถ๐’ฆ(๐œŽ) + ๐‘๐‘— โˆ’ ๐‘๐‘– (6) Since ๐ถ๐‘–(๐œŽ) = ๐ถ๐‘—(๏ฟฝฬ‡๏ฟฝ) โˆ’ ๐‘๐‘— + ๐‘๐‘– then ๐‘‘๐‘– โˆ’ ๐ถ๐‘–(๐œŽ) = ๐‘‘๐‘– โˆ’ ๐ถ๐‘—(๏ฟฝฬ‡๏ฟฝ) + ๐‘๐‘— โˆ’ ๐‘๐‘–.The condition (1), (2) implies, since ๐‘ ๐‘– โ‰ฅ ๐‘ ๐‘— then ๐‘‘๐‘– โˆ’ ๐‘๐‘– โˆ’ ๐ถ๐‘—(๏ฟฝฬ‡๏ฟฝ) โ‰ฅ ๐‘‘๐‘— โˆ’ ๐‘๐‘— โˆ’ ๐ถ๐‘—(๏ฟฝฬ‡๏ฟฝ) hence ๐‘‘๐‘– โˆ’ ๐‘๐‘– + ๐‘๐‘— โˆ’ ๐ถ๐‘—(๏ฟฝฬ‡๏ฟฝ) โ‰ฅ ๐‘‘๐‘— โˆ’ ๐ถ๐‘—(๏ฟฝฬ‡๏ฟฝ) from which we deduce that ๐ธ๐‘š๐‘Ž๐‘ฅ(๐œŽ) โ‰ฅ ๐ธ๐‘š๐‘Ž๐‘ฅ(๏ฟฝฬ‡๏ฟฝ) then โˆ‘๐ธ๐’ฆ(๐œŽ) โ‰ฅ โˆ‘๐ธ๐’ฆ(๏ฟฝฬ‡๏ฟฝ). IHJPAS. 37 (1) 2024 399 Then the addition in cost from this inequality is obtained from ( โˆ‘๐ธ(๐œŽ) = โˆ‘๐ธ๐’ฆ(๏ฟฝฬ‡๏ฟฝ) + (๐‘ ๐‘– โˆ’ ๐‘ ๐‘—) ๐‘‘๐‘– โ‰ฅ ๐‘‘๐‘— and ๐‘๐‘— โ‰ฅ ๐‘๐‘– this mean ๐‘๐‘— โˆ’ ๐‘๐‘– โ‰ฅ 0, hence ๐‘‘๐‘– โˆ’ ๐‘‘๐‘— + ๐‘๐‘— โˆ’ ๐‘๐‘– โ‰ฅ ๐‘๐‘— โˆ’ ๐‘๐‘–, and ๐‘ ๐‘– โˆ’ ๐‘ ๐‘— โ‰ฅ ๐‘๐‘— โˆ’ ๐‘๐‘–. Then โˆ‘๐ธ๐‘˜(๏ฟฝฬ‡๏ฟฝ) + (๐‘ ๐‘– โˆ’ ๐‘ ๐‘—) โ‰ฅ โˆ‘๐ธ๐’ฆ(๏ฟฝฬ‡๏ฟฝ) + ๐‘๐‘— โˆ’ ๐‘๐‘–, (by adding โˆ‘E๐’ฆ(ฯƒฬ‡) for both sides). from ( โˆ‘๐ธ๐’ฆ(๐œŽ) = โˆ‘๐ธ๐’ฆ(๏ฟฝฬ‡๏ฟฝ) + (๐‘ ๐‘– โˆ’ ๐‘ ๐‘—) and then โˆ‘๐ถ๐’ฆ(๐œŽ) + โˆ‘๐ธ๐’ฆ(๐œŽ) โ‰ฅ โˆ‘๐ถ๐’ฆ(๐œŽ) + ๐‘๐‘— โˆ’ ๐‘๐‘– + โˆ‘๐ธ๐’ฆ(๏ฟฝฬ‡๏ฟฝ), (by adding โˆ‘๐ถ๐‘˜(๐œŽ) for both sides). From Equation (6) there is โˆ‘๐ถ๐’ฆ(๐œŽ) + โˆ‘๐ธ๐’ฆ(๐œŽ) โ‰ค โˆ‘๐ถ๐’ฆ(๏ฟฝฬ‡๏ฟฝ) + โˆ‘๐ธ๐’ฆ(๏ฟฝฬ‡๏ฟฝ) (by adding ๐‘‡๐‘š๐‘Ž๐‘ฅ for both sides), finally โˆ‘๐ถ๐’ฆ(๐œŽ) + โˆ‘๐ธ๐’ฆ(๐œŽ) + ๐‘‡๐‘š๐‘Ž๐‘ฅ(๐œŽ) โ‰ค โˆ‘๐ถ๐‘˜(๏ฟฝฬ‡๏ฟฝ) + โˆ‘๐ธ๐’ฆ(๏ฟฝฬ‡๏ฟฝ) + ๐‘‡(๏ฟฝฬ‡๏ฟฝ) . Example (3): Letโ€™s use MSP with 5 jobs and processing time and due date as the following table: Table 4. The data of ๐‘๐‘— , ๐‘‘๐‘— , and ๐‘ ๐‘— for problem (๐‘†๐ถ๐‘†๐ธ๐‘‡) When using the Rule (1) we obtain the DRs mentioned in Figure (3). Figure (3): The DRs of the example (3). From Rule (1) there are (6) DRs, as can see: 1๏‚ฎ2, 1๏‚ฎ 3,1๏‚ฎ4, 1๏‚ฎ6, 2๏‚ฎ 6, 4๏‚ฎ2, 4๏‚ฎ 3, 4๏‚ฎ 6,5๏‚ฎ3. in Table 5, contain (7) likely sequences some /all are subject to the aforementioned DRs. The adjacency matrix ๐ด is as followings: ๐ด(๐บ) = [ 0 1 1 1 ๐‘Ž15 0 0 ๐‘Ž23 0 ๐‘Ž25 0 ๐‘Ž32 0 0 0 0 1 1 0 ๐‘Ž45 ๐‘Ž51 ๐‘Ž52 1 ๐‘Ž54 0 ] . where ๐‘Ž๐‘—๐‘– = { 1, if ๐‘Ž๐‘–๐‘— = 0 0, if ๐‘Ž๐‘–๐‘— = 1 . 1 2 3 4 5 ๐‘๐‘— 1 8 10 4 9 ๐‘‘๐‘— 14 28 27 23 12 ๐‘ ๐‘— 13 20 17 19 3 1 4 5 2 3 IHJPAS. 37 (1) 2024 400 Table 5. The efficient sequences for example (3) under DR EF-SQ ( ๐‘บ๐‘ช๐‘บ๐‘ฌ๐‘ป ) ๐‘บโ‚ฑ๐Ÿ• Seq. POS1 POS 2 POS 3 POS 4 POS 5 (โˆ‘๐‘ช๐’‹, โˆ‘๐‘ฌ๐’‹, ๐‘ป๐’Ž๐’‚๐’™) โˆ‘๐‘ช๐’‹ + โˆ‘๐‘ฌ๐’‹ + ๐‘ป๐’Ž๐’‚๐’™ 1 1 4 2 5 3 (73,46,10) 129 2 1 4 5 2 3 (74,37,5) 116 3 1 4 5 3 2 (76,34,4) 114 4 1 5 4 2 3 (79,30,5) 114 5 1 5 4 3 2 (81,27,5) 113 6 5 1 4 2 3 (87,22,4) 114 7 5 1 4 3 2 (89,19,4) 112 Where EF-SQ =efficient sequence, POS = position The sequences (1โ€“7) provide the problem ( ๐‘†๐ถ๐‘†๐ธ๐‘‡ ) an effective value and the sequence (7) an optimal value for the problem (Sโ‚ฑ7), as can be shown in Table 5. 6. Conclusions In this study, a mathematical model was created to address the research problems 1//๐น(โˆ‘๐ถ๐‘— , โˆ‘๐ธ๐‘— , ๐‘‡๐‘š๐‘Ž๐‘ฅ), 1// โˆ‘๐ถ๐‘— + โˆ‘๐ธ๐‘— + ๐‘‡๐‘š๐‘Ž๐‘ฅ. Discovered a straightforward algorithm for the efficient schedule for sub-problems for 1//๐น(โˆ‘๐ถ๐‘— , โˆ‘ ๐ธ๐‘— , ๐‘‡๐‘š๐‘Ž๐‘ฅ) and it was proven that some rules give efficient (optimal) solutions to these problems ( ๐‘†๐ถ๐‘†๐ธ๐‘‡ )and(Sโ‚ฑ7), finding and proving some special cases that find some efficient (optimal) solutions suitable for the problems ( ๐‘†๐ถ๐‘†๐ธ๐‘‡ )and(Sโ‚ฑ7). This paper has proved the efficacy of rules SPT and EDD and demonstrated the significance of the Dominance Rule (DR) that can be used in this problem to improve efficient solutions. In the future, it would be interesting to conduct a study on the following machine scheduling problems (MSPs). 1) 1/๐‘Ÿ๐‘—/ ๐น(โˆ‘๐ถ๐‘— , โˆ‘๐ธ๐‘— , ๐‘‡๐‘š๐‘Ž๐‘ฅ). 2) 1/๐‘Ÿ๐‘—/ โˆ‘ ๐ถ๐‘— + โˆ‘๐ธ๐‘— + ๐‘‡๐‘š๐‘Ž๐‘ฅ . 3) 1/๐‘†๐‘“/ ๐น(โˆ‘๐ถ๐‘— , โˆ‘ ๐ธ๐‘— , ๐‘‡๐‘š๐‘Ž๐‘ฅ). Acknowledgment The authors are greatly appreciated the referees for their valuable comments and suggestions for improving the paper Conflict of Interest The authors declare that they have no conflicts of interest. Funding There is no financial support in preparation for the publication. References 1. WASSENHOVE, L.N.V. Single Machine Scheduling to Minimize Total Late Work. Oper. Res. 1992, 40, 586โ€“595. https://doi:10.1287/opre.40.3.586. 2. Tanaev, V.; Gordon, W.; Shafransky, Y. M. Scheduling theory. Single-stage systems. Springer Science and Business Media. 2012. 3. Hoogeveen, H. Multicriteria Scheduling. Eur. J. Oper. 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