TY - JOUR AU - Gazdag-Tóth, Boglárka TI - Customer selection rules in competitive facility location JF - ANNALES MATHEMATICAE ET INFORMATICAE J2 - ANN MATH INFORM VL - Accepted manuscript PY - 2024 SN - 1787-5021 DO - 10.33039/ami.2024.02.003 UR - https://m2.mtmt.hu/api/publication/34871965 ID - 34871965 LA - English DB - MTMT ER - TY - JOUR AU - Szász, Attila AU - Bánhelyi, Balázs TI - Effective inclusion methods for verification of ReLU neural networks JF - ANNALES MATHEMATICAE ET INFORMATICAE J2 - ANN MATH INFORM PY - 2024 PG - 10 SN - 1787-5021 DO - 10.33039/ami.2024.02.007 UR - https://m2.mtmt.hu/api/publication/34729371 ID - 34729371 LA - English DB - MTMT ER - TY - JOUR AU - Homolya, Viktor AU - Vinkó, Tamás TI - Closeness centrality reconstruction of tree graphs JF - CENTRAL EUROPEAN JOURNAL OF OPERATIONS RESEARCH J2 - CEJOR VL - 2024 PY - 2024 PG - 28 SN - 1435-246X DO - 10.1007/s10100-023-00900-1 UR - https://m2.mtmt.hu/api/publication/34607749 ID - 34607749 AB - This paper deals with a problem which belongs to the general question: how to reconstruct a graph from limited amount of information. As given information, we use the closeness centrality, which assigns a non-negative number to each node of the graph in question: the reciprocal of the sum of the length of the shortest paths between the node and all other nodes in the graph. Here we consider the case when the original graph is a tree and it is also known which nodes are the leaves. Based on some theoretical results, three algorithms are proposed. The first one aims at finding a non-exact solution G(P) in short time; the second one is a metaheuristic with some variants, they are intended to give further improvement on G(P); and the third one is designed for giving accurate results. Detailed explanations of these algorithms are given, together with numerical experiments to demonstrate their efficiency. LA - English DB - MTMT ER - TY - JOUR AU - Tóth, Violetta AU - Heinc, Emília AU - Mikó, Edit AU - Csendes, Tibor AU - Bánhelyi, Balázs TI - Profitability Optimization of Dairy Farms: The Effect of Pregnancy Rate and Culling Decision JF - ANIMALS J2 - ANIMALS-BASEL VL - 14 PY - 2024 IS - 1 PG - 17 SN - 2076-2615 DO - 10.3390/ani14010018 UR - https://m2.mtmt.hu/api/publication/34480983 ID - 34480983 AB - One of the most important decisions in dairy cattle production today is the correct choice of culling time for cows. In the culling decision process, the farmer has to take into account a number of factors, the complexity of which makes the decision-making task difficult. A crucial factor is the evolution of reproductive indicators. The aim of the research was to develop a microsimulation method that can be used to easily investigate the impact on profitability of increasing pregnancy rates and when the culling decision is made. In the microsimulation, the stock was examined without changing any other conditions. A microsimulation method has been developed to determine with high accuracy the effect of the pregnancy rate and the increase in culling days on the economic indicators of individual dairy farms. By microsimulation, the effect of changing these two parameters on the expected milk production of cows, the most important economic indicator for cattle farms, was investigated. The other parameters of economic importance were simulated using a cattle farm database. The purpose of microsimulation is to assist in producing certain managerial decisions in order to achieve better profitability and economic efficiency. In summary, the results showed that increasing the pregnancy rate can successfully reduce the length of the calving interval, but the improved pregnancy rate did not show a significant increase in milk production. In order to obtain results that can be used by farms, the authors intend to further develop the model in the future, adapting it to farms and taking into account their specificities. LA - English DB - MTMT ER - TY - JOUR AU - Heinc, Emília AU - Bánhelyi, Balázs TI - Testing the selection heuristic of the Accelerated Branch and Bound method JF - ANNALES MATHEMATICAE ET INFORMATICAE J2 - ANN MATH INFORM PY - 2024 PG - 11 SN - 1787-5021 DO - 10.33039/ami.2024.02.006 UR - https://m2.mtmt.hu/api/publication/34177876 ID - 34177876 LA - English DB - MTMT ER - TY - JOUR AU - Heinc, Emília AU - Bánhelyi, Balázs TI - Comparing structural constraints for accelerated branch and bound solver of process network synthesis problems JF - ACTA CYBERNETICA J2 - ACTA CYBERN-SZEGED PY - 2024 PG - 25 SN - 0324-721X DO - 10.14232/actacyb.297735 UR - https://m2.mtmt.hu/api/publication/34177869 ID - 34177869 LA - English DB - MTMT ER - TY - JOUR AU - Gazdag-Tóth, Boglárka AU - Anton-Sanchez, Laura AU - Fernández, José TI - A Huff-like location model with quality adjustment and/or closing of existing facilities JF - EUROPEAN JOURNAL OF OPERATIONAL RESEARCH J2 - EJOR VL - 313 PY - 2024 IS - 3 SP - 937 EP - 953 PG - 17 SN - 0377-2217 DO - 10.1016/j.ejor.2023.08.054 UR - https://m2.mtmt.hu/api/publication/34139938 ID - 34139938 AB - The problem of an expanding chain in a given area is considered. It may locate a new facility, vary the quality of its existing facilities, close some of them, or a combination of all these possibilities, whatever is the best to maximize its profit, given a budget for the expansion. A new competitive location and design model is proposed that allows all these possibilities. The resulting model is a difficult to solve MINLP problem. A branch-and-bound method based on interval analysis is proposed to cope with it. The method can solve medium-size problems in a reasonable amount of CPU time. An ad-hoc heuristic and a hybrid method that usually find a near-optimal solution in a fraction of time of the exact method are also proposed. Some computational studies are presented to show the performance of the algorithms. (c) 2023 Elsevier B.V. All rights reserved. LA - English DB - MTMT ER - TY - JOUR AU - Szabó, Péter Gábor TI - ,,semmiből egy ujj más világot teremtettem". 200 éves Bolyai János híres temesvári levele. JF - MATLAP: IFJÚSÁGI MATEMATIKAI LAPOK J2 - MATLAP VL - 27 PY - 2023 IS - 9 SP - 306 EP - 308 PG - 3 SN - 1224-3140 UR - https://m2.mtmt.hu/api/publication/34681237 ID - 34681237 LA - Hungarian DB - MTMT ER - TY - CHAP AU - Szabó, Péter Gábor ED - Cristian, Réka Mónika ED - Kérchy, Anna TI - Eszter Klein (1910-2005): The Woman of the Happy End Problem T2 - Pioneer Hungarian Women in Science and Education II PB - Akadémiai Kiadó CY - Budapest SN - 9789634549277 PY - 2023 SP - 101 EP - 111 PG - 11 UR - https://m2.mtmt.hu/api/publication/34681230 ID - 34681230 LA - English DB - MTMT ER - TY - JOUR AU - Szabó, Péter Gábor TI - Elveszett Bolyai-relikviák nyomában: Bolyai János hegedűje. Dr. Gazda István tudománytörténész 75. születésnapjára TS - Dr. Gazda István tudománytörténész 75. születésnapjára JF - HALADVÁNY KIADVÁNY J2 - HALADVÁNY KIADVÁNY VL - 17 PY - 2023 SP - 1 EP - 8 PG - 8 UR - https://m2.mtmt.hu/api/publication/34681208 ID - 34681208 LA - Hungarian DB - MTMT ER -