TY - JOUR AU - Pituk, Mihály AU - Stavroulakis, John Ioannis TI - Characterization of shadowing for linear autonomous delay differential equations JF - CZECHOSLOVAK MATHEMATICAL JOURNAL J2 - CZECH MATH J VL - 2024 PY - 2024 SP - 1 EP - 8 PG - 8 SN - 0011-4642 DO - 10.21136/CMJ.2024.0191-23 UR - https://m2.mtmt.hu/api/publication/34780182 ID - 34780182 LA - English DB - MTMT ER - TY - CHAP AU - Medgyes, Krisztián AU - Kovács, Tamás ED - Hudoba, Péter ED - Szűcs, Judit ED - Guzsvinecz, Tibor TI - Measurements in a roundabout T2 - 10th Winter School for PhD Students in Informatics and Mathematics PB - Section of Mathematical and Information Sciences Association of Hungarian PhD and DLA Students CY - Budapest SN - 9786156457462 PY - 2024 SP - 26 UR - https://m2.mtmt.hu/api/publication/34777123 ID - 34777123 LA - English DB - MTMT ER - TY - CHAP AU - Medgyes, Ádám István AU - Medgyes, Krisztián ED - Hudoba, Péter ED - Szűcs, Judit ED - Guzsvinecz, Tibor TI - Transportation and delivery optimization. the role of information technology in enhancing efficiency and sustainability TS - the role of information technology in enhancing efficiency and sustainability T2 - 10th Winter School for PhD Students in Informatics and Mathematics PB - Section of Mathematical and Information Sciences Association of Hungarian PhD and DLA Students CY - Budapest SN - 9786156457462 PY - 2024 SP - 24 EP - 25 PG - 2 UR - https://m2.mtmt.hu/api/publication/34777110 ID - 34777110 LA - English DB - MTMT ER - TY - JOUR AU - Backes, Lucas AU - Dragičević, Davor AU - Pituk, Mihály TI - Shadowing, Hyers–Ulam stability and hyperbolicity for nonautonomous linear delay differential equations JF - COMMUNICATIONS IN CONTEMPORARY MATHEMATICS J2 - COMMUN CONTEMP MATH VL - 2024 PY - 2024 SN - 0219-1997 DO - 10.1142/S0219199724500123 UR - https://m2.mtmt.hu/api/publication/34765170 ID - 34765170 AB - It is known that hyperbolic nonautonomous linear delay differential equations in a finite dimensional space are Hyers–Ulam stable and hence shadowable. The converse result is available only in the special case of autonomous and periodic linear delay differential equations with a simple spectrum. In this paper, we prove the converse and hence the equivalence of all three notions in the title for a general class of nonautonomous linear delay differential equations with uniformly bounded coefficients. The importance of the boundedness assumption is shown by an example. LA - English DB - MTMT ER - TY - JOUR AU - Balázs, István AU - Fodor, Attila AU - Magyar, Attila TI - Short-term system imbalance forecast using linear and non-linear methods JF - ENERGY SYSTEMS: OPTIMIZATION MODELING SIMULATION AND ECONOMIC ASPECTS J2 - ENERGY SYSTEMS VL - 2024 PY - 2024 SN - 1868-3967 DO - 10.1007/s12667-024-00667-7 UR - https://m2.mtmt.hu/api/publication/34765160 ID - 34765160 AB - The imbalance between supply and demand is a critical factor in the operation of the power system, as it leads to a change in the system frequency. Therefore, it is essential to be able to predict its value from historical, measured and forecast data. Based on the assumption that system imbalance is correlated with measured values of system variables as well as predictions of exogenous variables, this work proposes a multi-step version of the autoregressive distributed lag model for the short-term forecast of system imbalance. The proposed forecasting model has been compared with a long short-term memory network-based procedure as well as with an extratree regression model using real data. The results show that the proposed multi-step autoregressive forecasting model outperforms the others in all three evaluation metrics. Since, in many cases, it is sufficient to specify the sign of the imbalance, this paper introduces the concept of sign accuracy as a function of the predicted imbalance and evaluates it for the investigated solutions. LA - English DB - MTMT ER - TY - JOUR AU - Kegyes, Tamás AU - Kummer, Alex AU - Süle, Zoltán AU - Abonyi, János TI - Generally Applicable Q-Table Compression Method and Its Application for Constrained Stochastic Graph Traversal Optimization Problems JF - INFORMATION (BASEL) J2 - INFORMATION-BASEL VL - 15 PY - 2024 IS - 4 SP - 193 SN - 2078-2489 DO - 10.3390/info15040193 UR - https://m2.mtmt.hu/api/publication/34762966 ID - 34762966 AB - We analyzed a special class of graph traversal problems, where the distances are stochastic, and the agent is restricted to take a limited range in one go. We showed that both constrained shortest Hamiltonian pathfinding problems and disassembly line balancing problems belong to the class of constrained shortest pathfinding problems, which can be represented as mixed-integer optimization problems. Reinforcement learning (RL) methods have proven their efficiency in multiple complex problems. However, researchers concluded that the learning time increases radically by growing the state- and action spaces. In continuous cases, approximation techniques are used, but these methods have several limitations in mixed-integer searching spaces. We present the Q-table compression method as a multistep method with dimension reduction, state fusion, and space compression techniques that project a mixed-integer optimization problem into a discrete one. The RL agent is then trained using an extended Q-value-based method to deliver a human-interpretable model for optimal action selection. Our approach was tested in selected constrained stochastic graph traversal use cases, and comparative results are shown to the simple grid-based discretization method. LA - English DB - MTMT ER - TY - JOUR AU - Gyarmati, László AU - Edvy, László AU - Mihálykó, Lajos Csaba AU - Mihálykóné Orbán, Éva TI - Decision support for sports selection based on performance measurement applying the generalized Thurstone method JF - INTERNATIONAL JOURNAL OF SPORTS SCIENCE AND COACHING J2 - INT J SPORT SCI COACHING PY - 2024 SN - 1747-9541 DO - 10.1177/17479541241240609 UR - https://m2.mtmt.hu/api/publication/34762107 ID - 34762107 AB - In this article, a new complex method is presented that supports decision-making in sports selection. The method consists of two different parts. The first one is the creation of the framework, that is the assessment of the opinions of trainers about the significance of some attributes in special sports. As a result, weights are constructed based on a generalized 7-option Thurstone method. The second part of the process involves assessing athletes’ performance from various perspectives. Finally, the calculated weights are combined with the performance of the athletes. The scores we obtain quantifiably indicate which sport is most likely to be recommended for a given individual. Moreover, the method developed allows us to quantifiably measure the strength of individual athletes and compare them across age groups equally. A computer program has been developed that implements the evaluation process in addition to this the evaluation results are also presented in this article. By extending this method, it can not only be used for sports selection but also for making various complex decisions where there are numerous possible outcomes to choose from. As a result of this research, we present a generalized set of criteria for the evaluation and describe the results obtained with the method. We explain the relationship between coaching decisions and the recommendations of the method and provide a method for determining the direction of future development for individual athletes. LA - English DB - MTMT ER - TY - JOUR AU - Caro, Yair AU - Patkós, Balázs AU - Tuza, Zsolt TI - Connected Turán number of trees JF - ARS MATHEMATICA CONTEMPORANEA J2 - ARS MATH CONTEMPOR VL - Manuscript Published 2023-10-03 PY - 2024 SP - & SN - 1855-3966 DO - 10.26493/1855-3974.3109.e4b UR - https://m2.mtmt.hu/api/publication/34760346 ID - 34760346 AB - As a variant of the much studied Turán number, ex(n,F), the largest number of edges that an n-vertex F-free graph may contain, we introduce the connected Turán number exc(n,F), the largest number of edges that an n-vertex connected F-free graph may contain. We focus on the case where the forbidden graph is a tree. The celebrated conjecture of Erdős and Sós states that for any tree T, we have ex(n,T)≤(|T|−2)n2. We address the problem how much smaller exc(n,T) can be, what is the smallest possible ratio of exc(n,T) and (|T|−2)n2 as |T| grows. We also determine the exact value of exc(n,T) for small trees, in particular for all trees with at most six vertices. We introduce general constructions of connected T-free graphs based on graph parameters as longest path, matching number, branching number, etc. LA - English DB - MTMT ER - TY - CHAP AU - Medgyes, Krisztián AU - Guzsvinecz, Tibor AU - Szűcs, Judit ED - Hudoba, Péter ED - Szűcs, Judit ED - Guzsvinecz, Tibor TI - Digital imaging and UAVs T2 - 10th Winter School for PhD Students in Informatics and Mathematics PB - Section of Mathematical and Information Sciences Association of Hungarian PhD and DLA Students CY - Budapest SN - 9786156457462 PY - 2024 SP - 27 EP - 27 PG - 1 UR - https://m2.mtmt.hu/api/publication/34752089 ID - 34752089 LA - English DB - MTMT ER - TY - CHAP AU - Gombkötő, Ákos AU - Szűcs, Judit AU - Guzsvinecz, Tibor ED - Hudoba, Péter ED - Szűcs, Judit ED - Guzsvinecz, Tibor TI - Optimizing Wireless Power Transfer - A Preliminary Study T2 - 10th Winter School for PhD Students in Informatics and Mathematics PB - Section of Mathematical and Information Sciences Association of Hungarian PhD and DLA Students CY - Budapest SN - 9786156457462 PY - 2024 SP - 23 EP - 23 PG - 1 UR - https://m2.mtmt.hu/api/publication/34752086 ID - 34752086 LA - English DB - MTMT ER -