TY - GEN A1 - Löffler, Sven A1 - Becker, Ilja A1 - Hofstedt, Petra T1 - Enhancing constraint optimization problems with greedy search and clustering: a focus on the traveling salesman problem T2 - Proceedings of the 16th International Conference on Agents and Artificial Intelligence - Volume 3: ICAART Y1 - 2024 SN - 978-989-758-680-4 U6 - https://doi.org/10.5220/0012453000003636 SN - 2184-433X SP - 1170 EP - 1178 PB - SCITEPRESS - Science and Technology Publications ER - TY - GEN A1 - Löffler, Sven A1 - Hofstedt, Petra T1 - A constraint-based greedy-local-global search for the warehouse location problem T2 - IFIP Advances in Information and Communication Technology Y1 - 2024 SN - 9783031632181 U6 - https://doi.org/10.1007/978-3-031-63219-8_22 SN - 1868-4238 SP - 291 EP - 304 PB - Springer Nature Switzerland CY - Cham ER - TY - GEN A1 - Frank, Florian A1 - Buckel, Peter A1 - Hoegner, Ludwig A1 - Hofstedt, Petra T1 - A landmark selection method for object-based visual outdoor localization approaches of automated ground vehicles T2 - ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences N2 - Autonomous vehicles must navigate independently in an outdoor environment using features or objects. However, some objects may be more or less suitable for localization due to their attributes. Therefore, this work investigates the suitability of landmarks for camera- and object-based outdoor localization methods. First, object attributes are methodically derived from the requirements of object-based localization. The physical representation on the camera image plane, probability of occurrence, and persistence were identified as influencing the object localization suitability. The influence of the object’s camera image plane representation regarding object recognition algorithms is not considered or discussed, but advice on the minimum object pixel size is provided. The first milestone was the creation of an equation for object localization suitability calculation by normalizing and multiplying the identified attributes. Simultaneously, potential objects from the outdoor environment were identified, resulting in a structured object catalog. The results of the equation and catalog are a ranked according to the object localization suitability in a comparison table. Our comparison demonstrates that objects such as buildings or trees are more suitable than street lane markings for self-localization. However, most current datasets do not include the proposed instantiated objects. The paper addresses this issue, assists in the object selection for outdoor localization methods and provides input for the creation of future-oriented datasets and autonomous driving maps. Y1 - 2024 U6 - https://doi.org/10.5194/isprs-annals-X-4-W5-2024-163-2024 SN - 2194-9050 SP - 163 EP - 169 PB - Copernicus GmbH ER - TY - GEN A1 - Becker, Ilja A1 - Löffler, Sven A1 - Hofstedt, Petra ED - Machado, Jose Manuel F. ED - Chamoso, Pablo ED - Hernandez, Guillermo ED - Bocewicz, Grzegorz ED - Loukanova, Roussanka ED - Jove, Esteban ED - del Rey, Angel Martin ED - Ricca, Michela T1 - ML-based Automation of Constraint Satisfaction Model Transformation and Solver Configuration T2 - Distributed Computing and Artificial Intelligence, Special Sessions - DCAI 2022, 19th International Conference KW - Constraint Programming KW - Machine Learning Y1 - 2022 SN - 978-3-031-23209-1 SN - 978-3-031-23210-7 SP - 177 EP - 183 PB - Springer CY - Cham ER - TY - GEN A1 - Löffler, Sven A1 - Becker, Ilja A1 - Hofstedt, Petra ED - Strauss, Christine ED - Amagasa, Toshiyuki ED - Kotsis, Gabriele ED - Tjoa, A Min ED - Khalil, Ismail T1 - A Finite-Domain Constraint-Based Approach on the Stockyard Planning Problem T2 - Database and Expert Systems Applications : 34th International Conference, DEXA 2023, Penang, Malaysia, August 28–30, 2023, Proceedings, Part II Y1 - 2023 SN - 978-3-031-39820-9 SN - 978-3-031-39821-6 SP - 126 EP - 133 PB - Springer CY - Cham ER - TY - GEN A1 - Bels, Maximilian A1 - Löffler, Sven A1 - Becker, Ilja A1 - Hofstedt, Petra ED - Rocha, Ana Paula ED - Steels, Luc ED - van den Herik, H. Jaap T1 - Constraint-Based Filtering and Evaluation of CSP Search Trees T2 - Proceedings of the 15th International Conference on Agents and Artificial Intelligence - ICAART 2023, Volume 3 KW - Constraint Programming KW - Artificial Intelligence Y1 - 2023 SN - 978-989-758-623-1 U6 - https://doi.org/10.5220/0011641100003393 SP - 220 EP - 227 PB - Scitepress ER - TY - GEN A1 - Löffler, Sven A1 - Becker, Ilja A1 - Bückert, Carlo A1 - Hofstedt, Petra ED - Gini, Giuseppina ED - Nijmeijer, Henk ED - Filev, Dimitar T1 - Enhanced Optimal Beacon Placement for Indoor Positioning: A Set Variable Based Constraint Programming Approach T2 - Proceedings of the 20th International Conference on Informatics in Control, Automation and Robotics : November 13-15, 2023, in Rome, Italy, volume 1 KW - Beacon Placement KW - Constraint Programming KW - Decision Support Systems KW - Artificial Intelligence Y1 - 2023 SN - 978-989-758-670-5 U6 - https://doi.org/10.5220/0012203400003543 SP - 70 EP - 79 PB - Scitepress ER - TY - GEN A1 - Löffler, Sven A1 - Becker, Ilja A1 - Hofstedt, Petra A1 - Nitze, Andre A1 - Hennig, Silvia A1 - Klinge, Alexander ED - Klein, Maike ED - Krupka, Daniel ED - Winter, Cornelia ED - Wohlgemuth, Volker T1 - Planung des Ländlichen On-Demand-Verkehr - Probleme, Analyse und Algorithmen T2 - Informatik 2023 : Designing Futures - Zukünfte gestalten : 26.-29. September 2023, Berlin Y1 - 2023 SN - 978-3-88579-731-9 U6 - https://doi.org/10.18420/inf2023_177 SP - 1739 EP - 1750 PB - Gesellschaft für Informatik e.V. CY - Berlin ER - TY - GEN A1 - Pißarek, Adele A1 - Hofstedt, Petra A1 - Löffler, Sven ED - Dassisti, Michele ED - Madani, Kurosh ED - Panetto, Herve T1 - Stockyard Planning and Optimization Using Intelligent Search T2 - Innovative Intelligent Industrial Production and Logistics Y1 - 2025 SN - 978-3-031-80775-6 U6 - https://doi.org/10.1007/978-3-031-80775-6_7 SN - 1865-0937 VL - 2 SP - 94 EP - 110 PB - Springer Nature Switzerland CY - Cham ER - TY - CHAP A1 - Löffler, Sven A1 - Hofstedt, Petra ED - Nicosia, Guiseppe ED - Ojha, Varun ED - Giesselbach, Sven ED - Pardalos, M. Panos ED - Umeton, Renato T1 - A constraint-based savings algorithm for the Traveling Salesman Problem T2 - Machine Learning, Optimization and Data Science : 10th International Conference, LOD 2024, Castiglione Della Pescaia, Italy, September 22-25, 2024, Revised Selected Papers N2 - There exists a plethora of NP-hard problems for which obtaining an exact solution is computationally intensive while an approximate solution can be rapidly computed. The Traveling Salesman Problem (TSP) stands out as a prominent example within this problem class, being equally significant in both research and industry sectors. Exact methods for solving the TSP are typically infeasible within acceptable timeframes beyond a certain instance size. Due to the NP-hardness of the problem, computational time requirements would quickly escalate to weeks, months, years, or even millennia. In contrast, heuristic approaches often yield sufficiently good solutions rapidly, typically within seconds or minutes. However, the drawback lies in their tendency to produce only locally optimal solutions, which may deviate significantly from a global optimum. Nevertheless, heuristic methods remain preferred in industry due to their ability to find satisfactory solutions within reasonable timeframes. It is worth noting that even marginal improvements in solutions can translate into significant cost savings in practice. Hence, there is a demand for methods capable of swiftly providing high-quality solutions while also continuously searching for further, better solutions over time. This work aims to combine two approaches: heuristic search (utilizing two simple greedy algorithms and the savings algorithm developed by Clarke and Wright) and exact search (constraint programming), to solve TSPs. Using various TSP instances, we demonstrate that our approach yields a better solution than purely local methods in at least 80% of the cases. Furthermore, within the given time limit of 5 min, the new approach identifies a solution that is more than twice as good compared to traditional COP methods. KW - Constraints KW - Optimization KW - Traveling Salesman Problem Y1 - 2025 SN - 9783031824838 U6 - https://doi.org/10.1007/978-3-031-82484-5_15 SN - 0302-9743 VL - 2 SP - 203 EP - 217 PB - Springer Nature Switzerland CY - Cham ER -