Open research questions in Scheduling and Optimization Algorithms
58 unresolved questions extracted from the limitations and future-work sections of 448 Scheduling and Optimization Algorithms papers in our library. Each links back to the study that raised it.
What the literature leaves open
The paper does not provide a lower bound on the asymptotic performance ratio of SDF. The analysis is limited to the case where each task has equal length processing time p. The paper does not consider other scheduling algorithms or objective functions.
A coupled task scheduling approximation algorithm for minimizing the sum of completion times · 2026 · DOIFuture research can focus on developing more efficient scheduling algorithms for the coupled task scheduling problem. Future research can explore the application of the results to other scheduling problems. Future research can investigate the use of other mathematical techniques to analyze the SDF algorithm.
A coupled task scheduling approximation algorithm for minimizing the sum of completion times · 2026 · DOIThe study identifies a gap in the literature on unrelated parallel machine scheduling. The study notes that previous studies have neglected the scenario in which a single machine is required to perform more than one job.
A hybrid approach to multi-objective unrelated parallel machine scheduling with a new interpretation of job batches and families · 2026 · DOICoordinating limited resources over time while respecting complex constraints. Dealing with the complexity of the disjunctive graph in FJSSP instances. Improving the efficiency and effectiveness of scheduling systems.
Existing methods are difficult to accurately sense and characterize the dynamic heterogeneous state of FMS. There is a need for a cooperative policy learning algorithm that can generate high-quality rescheduling schemes within milliseconds after equipment failure.
Optimizing real-time rescheduling mechanism for flexible manufacturing systems considering equipment fault disturbances using HGNN-PPO cooperative policy learning algorithm · 2026 · DOIThe future efforts will be made to improve the PPO algorithm to make the convergence faster and the algorithm can be operated in real time. The scope of the reward function will be enlarged to have more objective metrics of cost and energy saving. The model will be tested and verified in the real warehouse.
The traditional approaches of logistics scheduling are hard to adapt to the rapid changes of the operational conditions. The traditional approaches do not have self-adaptive optimization capability, which leads to unsmooth and high operational expenses. There is a need for a new approach to logistics scheduling that can adapt to changing conditions.
Traditional static scheduling modes are unable to adapt to dynamic operational environments. Reverse logistics networks have significant dynamic and uncertain characteristics, posing huge challenges to scheduling decisions. There is a need for more efficient and adaptive logistics systems.
Dynamic Scheduling Implementation of Reverse Logistics Network Simulation Based on Deep Reinforcement Learning · 2026 · DOIFluctuating raw material prices. Unpredictable market demand. Limited production capacity.
The need for efficient allocation of limited resources. The complexity of the assignment problem in various industries.
The complexity of the scheduling problem. The need to prioritize more critical or higher-value orders. The importance of on-time delivery.
Iterated greedy with strategic reconstruction for parallel machine problem with weighted tardiness and setup times · 2026 · DOIFuture research could explore adaptive PSO strategies, stochastic disruptions, or integration with IoT and digital twin technologies to further improve responsiveness, robustness, and sustainability in dynamic, Industry 4. Future research could explore multi-swarm or cooperative PSO strategies to improve convergence and solution quality in large-scale instances, and integrate stochastic disruptions to reflect dynamic production conditions.
Optimizing logistics and production flows for sustainability in green flexible job-shops · 2026 · DOIIn this paper, the makespan service level is maximized in the stochastic flexible job-shop scheduling problem when the uncertainty is machine related, which makes sense in numerous real-life applications. This enhances the relevance of the makespan service level, in particular when there is flexibility in the choice of machines on which operations are processed as in the FJSP. To solve the optimization problem, a tabu search approach is combined with an innovative scenario generation approach when dealing with machine-related uncertainty. New randomly generated instances are proposed for the stochastic flexible job-shop scheduling problem. Moreover, new bounds on the makespan service level are proposed and validated to enhance the tabu search, as well as two different strategies to further guide the exploration of the neighborhood. Computational experiments are presented and analyzed to validate our approach. We see various relevant perspectives to this work. The notion of critical machines as well as how to identify them in the stochastic FJSP are interesting to investigate, as it could help to design more efficient methods and, from a practical standpoint, could help to determine more robust schedules. Also, for a given scheduling horizon T, our problem can be used in an order acceptance approach, where jobs are only added in the set of jobs to schedule if the makespan service level is high enough.
Makespan service level for the flexible job-shop scheduling problem under machine-related uncertainty · 2026 · DOIFuture research can focus on improving the computational capacity and time constraint of the proposed approach. Future research can explore the application of the proposed approach to other manufacturing operations. Future research can investigate the potential limitations of the proposed approach.
An engineering lot scheduling strategy for capacity ramp-up in real-world semiconductor manufacturing operations · 2026 · DOIThe current practice of scheduling engineering lots is mainly based on human experience, leading to variability and inefficiency. There is a need for a systemized approach to prioritize engineering lots. The paper identifies the gap in the current practice and proposes a new approach.
An engineering lot scheduling strategy for capacity ramp-up in real-world semiconductor manufacturing operations · 2026 · DOILimited attention to multi-agent scenarios in prior work. Low sampling efficiency of diffusion-based and flow-based approaches. Misalignment between generative objectives and reward maximization.
Future research can focus on extending the results to other scheduling problems. Future research can focus on developing more efficient algorithms for solving fairness properties.
The paper identifies a gap in the study of fairness properties in scheduling problems. The paper identifies a need for a complete complexity landscape for satisfiability and decision versions of fairness properties.
The study does not explore hybrid approaches that integrate LP’s precision with SA’s flexibility. The study is limited to a case study of Laras Craft by Kahayu Larasati in Bali, Indonesia.
To apply the study to other industrial sectors. To compare the results with other optimization techniques. To use the study as a framework for using genetic algorithms in optimization problems.
GENETIC ALGORITHM-BASED OPTIMIZATION OF INTER-MACHINE DELAYS IN AUTOMATIVE MANUFACTURING · 2026 · DOIThe industrial sector faces obstacles in product development due to human-induced errors and machine operation errors. The automotive sector has delays in actual production, which can be addressed using optimization techniques.
GENETIC ALGORITHM-BASED OPTIMIZATION OF INTER-MACHINE DELAYS IN AUTOMATIVE MANUFACTURING · 2026 · DOILimited study has focused on hybrid flow shops with a concentration on energy-machine balanced production. Comparative studies between classical algorithms and modern metaheuristics are limited.
Optimisation of energy and machine balance in the hybrid flowshop scheduling problem using differential evolution · 2026 · DOIThe study does not suggest any future research directions. Potential future research directions could include evaluating the framework using real-world data or considering dynamic changes in the planning horizon.
MULTI-PERIOD STAFFING SCHEDULING OPTIMIZATION BASED ON COLUMN GENERATION AND NETWORK FLOW ALGORITHMS · 2026 · DOIThe study identifies a combinatorial optimization problem that requires a structured algorithm. The study notes that direct enumeration becomes computationally difficult due to the large number of possible schedules.
MULTI-PERIOD STAFFING SCHEDULING OPTIMIZATION BASED ON COLUMN GENERATION AND NETWORK FLOW ALGORITHMS · 2026 · DOIEmerging research directions involving artificial intelligence, machine learning, fuzzy optimization, and dynamic decision-making. Integration with Artificial Intelligence and Machine Learning techniques for predictive resource allocation and intelligent scheduling.
Most-cited papers in Scheduling and Optimization Algorithms
- Integrated Production and Outbound Distribution Scheduling: Review and Extensions · Operations Research · 2009 · 463 citations
- One-Machine Sequencing to Minimize Certain Functions of Job Tardiness · Operations Research · 1969 · 251 citations
- Multi-resource constrained flexible job shop scheduling problem with fixture-pallet combinatorial optimisation · Computers & Industrial Engineering · 2024 · 124 citations
- Hybrid quantum particle swarm optimization and variable neighborhood search for flexible job-shop scheduling problem · Journal of Manufacturing Systems · 2024 · 113 citations
- A dual population collaborative genetic algorithm for solving flexible job shop scheduling problem with AGV · Swarm and Evolutionary Computation · 2024 · 110 citations
- Machine-fixture-pallet resources constrained flexible job shop scheduling considering loading and unloading times under pallet automation system · Journal of Manufacturing Systems · 2024 · 101 citations
- Deep reinforcement learning-based memetic algorithm for energy-aware flexible job shop scheduling with multi-AGV · Computers & Industrial Engineering · 2024 · 100 citations
- A <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si13.svg" display="inline" id="d1e4047"><mml:mi>Q</mml:mi></mml:math>-Learning based NSGA-II for dynamic flexible job shop scheduling with limited transportation resources · Swarm and Evolutionary Computation · 2024 · 99 citations
- The Human Planning and Scheduling Role in Advanced Manufacturing Systems: An Emerging Human Factors Domain · Human Factors The Journal of the Human Factors and Ergonomics Society · 1989 · 98 citations
- A DQN-based memetic algorithm for energy-efficient job shop scheduling problem with integrated limited AGVs · Swarm and Evolutionary Computation · 2024 · 94 citations
Most recent work
- Optimizing logistics and production flows for sustainability in green flexible job-shops · Acta Logistica · 2026
- A Q-learning-based variable greedy algorithm to minimize the sum of total earliness and tardiness in a no-wait flowshop scheduling problem · Computers & Operations Research · 2026
- Compatibility graphs in scheduling for batch processing machines with setup times · Discrete Mathematics, Algorithms and Applications · 2026
- Genetic Programming with Adaptive Population Restructuring for Dynamic Flexible Job Shop Scheduling · Mathematics · 2026
- Optimization of hybrid flow shop scheduling with batch processing and variable sublots via a multi-agent deep reinforcement learning–guided hybrid algorithm · Computers and Electrical Engineering · 2026
- Makespan service level for the flexible job-shop scheduling problem under machine-related uncertainty · Annals of Operations Research · 2026
- Minimizing total weighted tardiness in parallel machine scheduling with sequence-dependent setup times <i>via</i> fine-tuned large language models · Engineering Optimization · 2026
- Lot Streaming Optimization in Flexible Job Shop Scheduling via Deep Reinforcement Learning · Machines · 2026
- An engineering lot scheduling strategy for capacity ramp-up in real-world semiconductor manufacturing operations · Flexible Services and Manufacturing Journal · 2026
- Tardy jobs minimization in a dynamic job-shop environment using double Q-Learning Algorithm · RAIRO - Operations Research · 2026
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