[{"year":"2024","corporate_editor":["Mehwish Alam"],"quality_controlled":"1","title":"FaVEL: Fact Validation Ensemble Learning","date_created":"2024-11-19T14:12:49Z","abstract":[{"text":"Validating assertions before adding them to a knowledge graph is an essential part of its creation and maintenance. Due to the sheer size of knowledge graphs, automatic fact-checking approaches have been developed. These approaches rely on reference knowledge to decide whether a given assertion is correct. Recent hybrid approaches achieve good results by including several knowledge sources. However, it is often impractical to provide a sheer quantity of textual knowledge or generate embedding models to leverage these hybrid approaches. We present FaVEL, an approach that uses algorithm selection and ensemble learning to amalgamate several existing fact-checking approaches that rely solely on a reference knowledge graph and, hence, use fewer resources than current hybrid approaches. For our evaluation, we create updated versions of two existing datasets and a new dataset dubbed FaVEL-DS. Our evaluation compares our approach to 15 fact-checking approaches—including the state-of-the-art approach HybridFC—on 3 datasets. Our results demonstrate that FaVEL outperforms all other approaches significantly by at least 0.04 in terms of the area under the ROC curve. Our source code, datasets, and evaluation results are open-source and can be found at https://github.com/dice-group/favel.","lang":"eng"}],"file":[{"content_type":"application/pdf","success":1,"relation":"main_file","date_updated":"2024-11-19T14:14:14Z","creator":"uqudus","date_created":"2024-11-19T14:14:14Z","file_size":190661,"file_name":"favel.pdf","access_level":"closed","file_id":"57241"}],"publication":"EKAW 2024","ddc":["600"],"keyword":["fact checking","ensemble learning","transfer learning","knowledge management."],"language":[{"iso":"eng"}],"citation":{"chicago":"Qudus, Umair, Michael Röder, Franck Lionel Tatkeu Pekarou, Ana Alexandra Morim da Silva, and Axel-Cyrille Ngonga Ngomo. “FaVEL: Fact Validation Ensemble Learning.” In <i>EKAW 2024</i>, edited by Marco Rospocher and Mehwish Alam, 2024.","ieee":"U. Qudus, M. Röder, F. L. Tatkeu Pekarou, A. A. Morim da Silva, and A.-C. Ngonga Ngomo, “FaVEL: Fact Validation Ensemble Learning,” in <i>EKAW 2024</i>, Amsterdam, Netherlands, 2024.","ama":"Qudus U, Röder M, Tatkeu Pekarou FL, Morim da Silva AA, Ngonga Ngomo A-C. FaVEL: Fact Validation Ensemble Learning. In: Rospocher M, Mehwish Alam, eds. <i>EKAW 2024</i>. ; 2024.","bibtex":"@inproceedings{Qudus_Röder_Tatkeu Pekarou_Morim da Silva_Ngonga Ngomo_2024, title={FaVEL: Fact Validation Ensemble Learning}, booktitle={EKAW 2024}, author={Qudus, Umair and Röder, Michael and Tatkeu Pekarou, Franck Lionel and Morim da Silva, Ana Alexandra and Ngonga Ngomo, Axel-Cyrille}, editor={Rospocher, Marco and Mehwish Alam}, year={2024} }","short":"U. Qudus, M. Röder, F.L. Tatkeu Pekarou, A.A. Morim da Silva, A.-C. Ngonga Ngomo, in: M. Rospocher, Mehwish Alam (Eds.), EKAW 2024, 2024.","mla":"Qudus, Umair, et al. “FaVEL: Fact Validation Ensemble Learning.” <i>EKAW 2024</i>, edited by Marco Rospocher and Mehwish Alam, 2024.","apa":"Qudus, U., Röder, M., Tatkeu Pekarou, F. L., Morim da Silva, A. A., &#38; Ngonga Ngomo, A.-C. (2024). FaVEL: Fact Validation Ensemble Learning. In M. Rospocher &#38; Mehwish Alam (Eds.), <i>EKAW 2024</i>."},"has_accepted_license":"1","conference":{"name":"24th International Conference on Knowledge Engineering and Knowledge Management","start_date":"2024-11-26","end_date":"2024-11-28","location":"Amsterdam, Netherlands"},"date_updated":"2025-09-11T09:48:12Z","author":[{"first_name":"Umair","full_name":"Qudus, Umair","id":"83392","orcid":"0000-0001-6714-8729","last_name":"Qudus"},{"full_name":"Röder, Michael","id":"67199","last_name":"Röder","orcid":"https://orcid.org/0000-0002-8609-8277","first_name":"Michael"},{"full_name":"Tatkeu Pekarou, Franck Lionel","last_name":"Tatkeu Pekarou","first_name":"Franck Lionel"},{"last_name":"Morim da Silva","full_name":"Morim da Silva, Ana Alexandra","id":"72108","first_name":"Ana Alexandra"},{"first_name":"Axel-Cyrille","last_name":"Ngonga Ngomo","full_name":"Ngonga Ngomo, Axel-Cyrille","id":"65716"}],"editor":[{"first_name":"Marco","full_name":"Rospocher, Marco","last_name":"Rospocher"}],"status":"public","type":"conference","popular_science":"1","file_date_updated":"2024-11-19T14:14:14Z","project":[{"_id":"412","name":"NEBULA: Nutzerzentrierte KI-basierte Erkennung von Fake-News und Fehlinformationen"},{"_id":"285","name":"SAIL: SAIL - Nachhaltiger Lebenszyklus von intelligenten soziotechnischen Systemen"},{"_id":"410","name":"KnowGraphs: KnowGraphs: Knowledge Graphs at Scale"}],"_id":"57240","user_id":"83392","department":[{"_id":"34"}]},{"type":"conference","editor":[{"first_name":"Terry","full_name":"R. Payne, Terry","last_name":"R. Payne"},{"first_name":"Valentina","full_name":"Presutti, Valentina","last_name":"Presutti"},{"first_name":"Guilin","last_name":"Qi","full_name":"Qi, Guilin"},{"first_name":"María","full_name":"Poveda-Villalón, María","last_name":"Poveda-Villalón"},{"full_name":"Stoilos, Giorgos","last_name":"Stoilos","first_name":"Giorgos"},{"first_name":"Laura","full_name":"Hollink, Laura","last_name":"Hollink"},{"last_name":"Kaoudi","full_name":"Kaoudi, Zoi","first_name":"Zoi"},{"last_name":"Cheng","full_name":"Cheng, Gong","first_name":"Gong"},{"first_name":"Juanzi","full_name":"Li, Juanzi","last_name":"Li"}],"status":"public","_id":"50479","project":[{"grant_number":"860801","name":"KnowGraphs: KnowGraphs: Knowledge Graphs at Scale","_id":"410"}],"department":[{"_id":"34"}],"user_id":"83392","series_title":" Lecture Notes in Computer Science","file_date_updated":"2024-01-13T11:25:48Z","has_accepted_license":"1","publication_identifier":{"isbn":["9783031472398","9783031472404"],"issn":["0302-9743","1611-3349"]},"publication_status":"published","place":"Cham","intvolume":"     14265","page":"465–483","citation":{"mla":"Qudus, Umair, et al. “TemporalFC: A Temporal Fact Checking Approach over Knowledge Graphs.” <i>The Semantic Web – ISWC 2023</i>, edited by Terry R. Payne et al., vol. 14265, Springer, Cham, 2023, pp. 465–483, doi:<a href=\"https://doi.org/10.1007/978-3-031-47240-4_25\">10.1007/978-3-031-47240-4_25</a>.","bibtex":"@inproceedings{Qudus_Röder_Kirrane_Ngomo_2023, place={Cham}, series={ Lecture Notes in Computer Science}, title={TemporalFC: A Temporal Fact Checking Approach over Knowledge Graphs}, volume={14265}, DOI={<a href=\"https://doi.org/10.1007/978-3-031-47240-4_25\">10.1007/978-3-031-47240-4_25</a>}, booktitle={The Semantic Web – ISWC 2023}, publisher={Springer, Cham}, author={Qudus, Umair and Röder, Michael and Kirrane, Sabrina and Ngomo, Axel-Cyrille Ngonga}, editor={R. Payne, Terry and Presutti, Valentina and Qi, Guilin and Poveda-Villalón, María and Stoilos, Giorgos and Hollink, Laura and Kaoudi, Zoi and Cheng, Gong and Li, Juanzi}, year={2023}, pages={465–483}, collection={ Lecture Notes in Computer Science} }","short":"U. Qudus, M. Röder, S. Kirrane, A.-C.N. Ngomo, in: T. R. Payne, V. Presutti, G. Qi, M. Poveda-Villalón, G. Stoilos, L. Hollink, Z. Kaoudi, G. Cheng, J. Li (Eds.), The Semantic Web – ISWC 2023, Springer, Cham, Cham, 2023, pp. 465–483.","apa":"Qudus, U., Röder, M., Kirrane, S., &#38; Ngomo, A.-C. N. (2023). TemporalFC: A Temporal Fact Checking Approach over Knowledge Graphs. In T. R. Payne, V. Presutti, G. Qi, M. Poveda-Villalón, G. Stoilos, L. Hollink, Z. Kaoudi, G. Cheng, &#38; J. Li (Eds.), <i>The Semantic Web – ISWC 2023</i> (Vol. 14265, pp. 465–483). Springer, Cham. <a href=\"https://doi.org/10.1007/978-3-031-47240-4_25\">https://doi.org/10.1007/978-3-031-47240-4_25</a>","ieee":"U. Qudus, M. Röder, S. Kirrane, and A.-C. N. Ngomo, “TemporalFC: A Temporal Fact Checking Approach over Knowledge Graphs,” in <i>The Semantic Web – ISWC 2023</i>, Athens, Greece, 2023, vol. 14265, pp. 465–483, doi: <a href=\"https://doi.org/10.1007/978-3-031-47240-4_25\">10.1007/978-3-031-47240-4_25</a>.","chicago":"Qudus, Umair, Michael Röder, Sabrina Kirrane, and Axel-Cyrille Ngonga Ngomo. “TemporalFC: A Temporal Fact Checking Approach over Knowledge Graphs.” In <i>The Semantic Web – ISWC 2023</i>, edited by Terry R. Payne, Valentina Presutti, Guilin Qi, María Poveda-Villalón, Giorgos Stoilos, Laura Hollink, Zoi Kaoudi, Gong Cheng, and Juanzi Li, 14265:465–483.  Lecture Notes in Computer Science. Cham: Springer, Cham, 2023. <a href=\"https://doi.org/10.1007/978-3-031-47240-4_25\">https://doi.org/10.1007/978-3-031-47240-4_25</a>.","ama":"Qudus U, Röder M, Kirrane S, Ngomo A-CN. TemporalFC: A Temporal Fact Checking Approach over Knowledge Graphs. In: R. Payne T, Presutti V, Qi G, et al., eds. <i>The Semantic Web – ISWC 2023</i>. Vol 14265.  Lecture Notes in Computer Science. Springer, Cham; 2023:465–483. doi:<a href=\"https://doi.org/10.1007/978-3-031-47240-4_25\">10.1007/978-3-031-47240-4_25</a>"},"jel":["C"],"date_updated":"2024-01-13T11:48:28Z","volume":14265,"author":[{"first_name":"Umair","last_name":"Qudus","full_name":"Qudus, Umair"},{"full_name":"Röder, Michael","last_name":"Röder","first_name":"Michael"},{"first_name":"Sabrina","last_name":"Kirrane","full_name":"Kirrane, Sabrina"},{"last_name":"Ngomo","full_name":"Ngomo, Axel-Cyrille Ngonga","first_name":"Axel-Cyrille Ngonga"}],"conference":{"end_date":"2023-11-10","location":"Athens, Greece","name":"The Semantic Web – ISWC 2023","start_date":"2023-11-06"},"doi":"10.1007/978-3-031-47240-4_25","publication":"The Semantic Web – ISWC 2023","abstract":[{"text":"Verifying assertions is an essential part of creating and maintaining knowledge graphs. Most often, this task cannot be carried out manually due to the sheer size of modern knowledge graphs. Hence, automatic fact-checking approaches have been proposed over the last decade. These approaches aim to compute automatically whether a given assertion is correct or incorrect. However, most fact-checking approaches are binary classifiers that fail to consider the volatility of some assertions, i.e., the fact that such assertions are only valid at certain times or for specific time intervals. Moreover, the few approaches able to predict when an assertion was valid (i.e., time-point prediction approaches) rely on manual feature engineering. This paper presents TEMPORALFC, a temporal fact-checking approach that uses multiple sources of background knowledge to assess the veracity and temporal validity of a given assertion. We evaluate TEMPORALFC on two datasets and compare it to the state of the art in fact-checking and time-point prediction. Our results suggest that TEMPORALFC outperforms the state of the art on the fact-checking task by 0.13 to 0.15 in terms of Area Under the Receiver Operating Characteristic curve and on the time-point prediction task by 0.25 to 0.27 in terms of Mean Reciprocal Rank. Our code is open-source and can be found at https://github.com/dice-group/TemporalFC.","lang":"eng"}],"file":[{"file_size":1944818,"file_id":"50480","file_name":"ISWC 2023 TemporalFC-A Temporal Fact Checking approach over Knowledge Graphs.pdf","access_level":"closed","date_updated":"2024-01-13T11:25:48Z","creator":"uqudus","date_created":"2024-01-13T11:25:48Z","success":1,"relation":"main_file","content_type":"application/pdf"}],"keyword":["temporal fact checking · ensemble learning · transfer learning · time-point prediction · temporal knowledge graphs"],"ddc":["006"],"language":[{"iso":"eng"}],"year":"2023","publisher":"Springer, Cham","date_created":"2024-01-13T11:22:15Z","title":"TemporalFC: A Temporal Fact Checking Approach over Knowledge Graphs"},{"year":"2023","citation":{"ama":"Demir C, Wiebesiek M, Lu R, Ngonga Ngomo A-C, Heindorf S. LitCQD: Multi-Hop Reasoning in Incomplete Knowledge Graphs with Numeric Literals. <i>ECML PKDD</i>. Published online 2023.","ieee":"C. Demir, M. Wiebesiek, R. Lu, A.-C. Ngonga Ngomo, and S. Heindorf, “LitCQD: Multi-Hop Reasoning in Incomplete Knowledge Graphs with Numeric Literals,” <i>ECML PKDD</i>, 2023.","chicago":"Demir, Caglar, Michel Wiebesiek, Renzhong Lu, Axel-Cyrille Ngonga Ngomo, and Stefan Heindorf. “LitCQD: Multi-Hop Reasoning in Incomplete Knowledge Graphs with Numeric Literals.” <i>ECML PKDD</i>, 2023.","short":"C. Demir, M. Wiebesiek, R. Lu, A.-C. Ngonga Ngomo, S. Heindorf, ECML PKDD (2023).","mla":"Demir, Caglar, et al. “LitCQD: Multi-Hop Reasoning in Incomplete Knowledge Graphs with Numeric Literals.” <i>ECML PKDD</i>, 2023.","bibtex":"@article{Demir_Wiebesiek_Lu_Ngonga Ngomo_Heindorf_2023, title={LitCQD: Multi-Hop Reasoning in Incomplete Knowledge Graphs with Numeric Literals}, journal={ECML PKDD}, author={Demir, Caglar and Wiebesiek, Michel and Lu, Renzhong and Ngonga Ngomo, Axel-Cyrille and Heindorf, Stefan}, year={2023} }","apa":"Demir, C., Wiebesiek, M., Lu, R., Ngonga Ngomo, A.-C., &#38; Heindorf, S. (2023). LitCQD: Multi-Hop Reasoning in Incomplete Knowledge Graphs with Numeric Literals. <i>ECML PKDD</i>. European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases, Torino."},"has_accepted_license":"1","title":"LitCQD: Multi-Hop Reasoning in Incomplete Knowledge Graphs with Numeric Literals","conference":{"name":"European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases","location":"Torino"},"oa":"1","date_updated":"2024-03-06T16:18:53Z","date_created":"2023-08-01T09:24:21Z","author":[{"last_name":"Demir","full_name":"Demir, Caglar","id":"43817","first_name":"Caglar"},{"first_name":"Michel","full_name":"Wiebesiek, Michel","last_name":"Wiebesiek"},{"first_name":"Renzhong","full_name":"Lu, Renzhong","last_name":"Lu"},{"first_name":"Axel-Cyrille","id":"65716","full_name":"Ngonga Ngomo, Axel-Cyrille","last_name":"Ngonga Ngomo"},{"first_name":"Stefan","last_name":"Heindorf","orcid":"0000-0002-4525-6865","id":"11871","full_name":"Heindorf, Stefan"}],"file":[{"relation":"main_file","content_type":"application/pdf","file_size":562759,"file_id":"46249","file_name":"public.pdf","access_level":"open_access","date_updated":"2023-08-01T09:24:15Z","date_created":"2023-08-01T09:24:15Z","creator":"cdemir"}],"status":"public","type":"journal_article","publication":"ECML PKDD","ddc":["000"],"language":[{"iso":"eng"}],"file_date_updated":"2023-08-01T09:24:15Z","project":[{"grant_number":"101070305","name":"ENEXA: Efficient Explainable Learning on Knowledge Graphs","_id":"407"},{"name":"KnowGraphs: KnowGraphs: Knowledge Graphs at Scale","_id":"410","grant_number":"860801"},{"grant_number":"NW21-059D","_id":"285","name":"SAIL: SAIL: SustAInable Life-cycle of Intelligent Socio-Technical Systems"}],"_id":"46248","user_id":"14931","department":[{"_id":"574"},{"_id":"760"}]},{"doi":"https://doi.org/10.1007/978-3-031-33455-9_13","conference":{"name":"20th Extended Semantic Web Conference","start_date":"2023-05-28","end_date":"2023-06-01","location":"Hersonissos, Crete, Greece"},"main_file_link":[{"open_access":"1","url":"https://2023.eswc-conferences.org/wp-content/uploads/2023/05/paper_Kouagou_2023_Neural.pdf"}],"volume":13870,"author":[{"first_name":"N'Dah Jean","full_name":"KOUAGOU, N'Dah Jean","id":"87189","last_name":"KOUAGOU"},{"first_name":"Stefan","id":"11871","full_name":"Heindorf, Stefan","orcid":"0000-0002-4525-6865","last_name":"Heindorf"},{"first_name":"Caglar","last_name":"Demir","full_name":"Demir, Caglar","id":"43817"},{"last_name":"Ngonga Ngomo","full_name":"Ngonga Ngomo, Axel-Cyrille","id":"65716","first_name":"Axel-Cyrille"}],"date_updated":"2023-07-02T18:10:02Z","oa":"1","intvolume":"     13870","page":"209 - 226","citation":{"mla":"KOUAGOU, N’Dah Jean, et al. “Neural Class Expression Synthesis.” <i>The Semantic Web - 20th Extended Semantic Web Conference (ESWC 2023)</i>, edited by Catia Pesquita et al., vol. 13870, Springer International Publishing, 2023, pp. 209–26, doi:<a href=\"https://doi.org/10.1007/978-3-031-33455-9_13\">https://doi.org/10.1007/978-3-031-33455-9_13</a>.","bibtex":"@inproceedings{KOUAGOU_Heindorf_Demir_Ngonga Ngomo_2023, title={Neural Class Expression Synthesis}, volume={13870}, DOI={<a href=\"https://doi.org/10.1007/978-3-031-33455-9_13\">https://doi.org/10.1007/978-3-031-33455-9_13</a>}, booktitle={The Semantic Web - 20th Extended Semantic Web Conference (ESWC 2023)}, publisher={Springer International Publishing}, author={KOUAGOU, N’Dah Jean and Heindorf, Stefan and Demir, Caglar and Ngonga Ngomo, Axel-Cyrille}, editor={Pesquita, Catia and Jimenez-Ruiz, Ernesto and McCusker, Jamie and Faria, Daniel and Dragoni, Mauro and Dimou, Anastasia and Troncy, Raphael and Hertling, Sven}, year={2023}, pages={209–226} }","short":"N.J. KOUAGOU, S. Heindorf, C. Demir, A.-C. Ngonga Ngomo, in: C. Pesquita, E. Jimenez-Ruiz, J. McCusker, D. Faria, M. Dragoni, A. Dimou, R. Troncy, S. Hertling (Eds.), The Semantic Web - 20th Extended Semantic Web Conference (ESWC 2023), Springer International Publishing, 2023, pp. 209–226.","apa":"KOUAGOU, N. J., Heindorf, S., Demir, C., &#38; Ngonga Ngomo, A.-C. (2023). Neural Class Expression Synthesis. In C. Pesquita, E. Jimenez-Ruiz, J. McCusker, D. Faria, M. Dragoni, A. Dimou, R. Troncy, &#38; S. Hertling (Eds.), <i>The Semantic Web - 20th Extended Semantic Web Conference (ESWC 2023)</i> (Vol. 13870, pp. 209–226). Springer International Publishing. <a href=\"https://doi.org/10.1007/978-3-031-33455-9_13\">https://doi.org/10.1007/978-3-031-33455-9_13</a>","ama":"KOUAGOU NJ, Heindorf S, Demir C, Ngonga Ngomo A-C. Neural Class Expression Synthesis. In: Pesquita C, Jimenez-Ruiz E, McCusker J, et al., eds. <i>The Semantic Web - 20th Extended Semantic Web Conference (ESWC 2023)</i>. Vol 13870. Springer International Publishing; 2023:209-226. doi:<a href=\"https://doi.org/10.1007/978-3-031-33455-9_13\">https://doi.org/10.1007/978-3-031-33455-9_13</a>","ieee":"N. J. KOUAGOU, S. Heindorf, C. Demir, and A.-C. Ngonga Ngomo, “Neural Class Expression Synthesis,” in <i>The Semantic Web - 20th Extended Semantic Web Conference (ESWC 2023)</i>, Hersonissos, Crete, Greece, 2023, vol. 13870, pp. 209–226, doi: <a href=\"https://doi.org/10.1007/978-3-031-33455-9_13\">https://doi.org/10.1007/978-3-031-33455-9_13</a>.","chicago":"KOUAGOU, N’Dah Jean, Stefan Heindorf, Caglar Demir, and Axel-Cyrille Ngonga Ngomo. “Neural Class Expression Synthesis.” In <i>The Semantic Web - 20th Extended Semantic Web Conference (ESWC 2023)</i>, edited by Catia Pesquita, Ernesto Jimenez-Ruiz, Jamie McCusker, Daniel Faria, Mauro Dragoni, Anastasia Dimou, Raphael Troncy, and Sven Hertling, 13870:209–26. Springer International Publishing, 2023. <a href=\"https://doi.org/10.1007/978-3-031-33455-9_13\">https://doi.org/10.1007/978-3-031-33455-9_13</a>."},"publication_identifier":{"unknown":["978-3-031-33455-9"]},"publication_status":"published","department":[{"_id":"574"},{"_id":"760"}],"user_id":"11871","_id":"33734","project":[{"_id":"410","name":"KnowGraphs: KnowGraphs: Knowledge Graphs at Scale"},{"grant_number":"101070305","_id":"407","name":"ENEXA: Efficient Explainable Learning on Knowledge Graphs"},{"name":"SAIL: SAIL: SustAInable Life-cycle of Intelligent Socio-Technical Systems","_id":"285","grant_number":"NW21-059D"}],"status":"public","editor":[{"first_name":"Catia","full_name":"Pesquita, Catia","last_name":"Pesquita"},{"first_name":"Ernesto","last_name":"Jimenez-Ruiz","full_name":"Jimenez-Ruiz, Ernesto"},{"first_name":"Jamie","last_name":"McCusker","full_name":"McCusker, Jamie"},{"full_name":"Faria, Daniel","last_name":"Faria","first_name":"Daniel"},{"full_name":"Dragoni, Mauro","last_name":"Dragoni","first_name":"Mauro"},{"full_name":"Dimou, Anastasia","last_name":"Dimou","first_name":"Anastasia"},{"first_name":"Raphael","full_name":"Troncy, Raphael","last_name":"Troncy"},{"first_name":"Sven","full_name":"Hertling, Sven","last_name":"Hertling"}],"type":"conference","title":"Neural Class Expression Synthesis","date_created":"2022-10-15T19:20:11Z","publisher":"Springer International Publishing","year":"2023","language":[{"iso":"eng"}],"keyword":["Neural network","Concept learning","Description logics"],"external_id":{"unknown":["https://link.springer.com/chapter/10.1007/978-3-031-33455-9_13"]},"abstract":[{"lang":"eng","text":"Many applications require explainable node classification in knowledge graphs. Towards this end, a popular ``white-box'' approach is class expression learning: Given sets of positive and negative nodes, class expressions in description logics are learned that separate positive from negative nodes. Most existing approaches are search-based approaches generating many candidate class expressions and selecting the best one. However, they often take a long time to find suitable class expressions. In this paper, we cast class expression learning as a translation problem and propose a new family of class expression learning approaches which we dub neural class expression synthesizers. Training examples are ``translated'' into class expressions in a fashion akin to machine translation. Consequently, our synthesizers are not subject to the runtime limitations of search-based approaches. We study three instances of this novel family of approaches based on LSTMs, GRUs, and set transformers, respectively. An evaluation of our approach on four benchmark datasets suggests that it can effectively synthesize high-quality class expressions with respect to the input examples in approximately one second on average. Moreover, a comparison to state-of-the-art approaches suggests that we achieve better F-measures on large datasets. For reproducibility purposes, we provide our implementation as well as pretrained models in our public GitHub repository at https://github.com/dice-group/NeuralClassExpressionSynthesis"}],"publication":"The Semantic Web - 20th Extended Semantic Web Conference (ESWC 2023)"},{"year":"2023","citation":{"apa":"Demir, C., &#38; Ngonga Ngomo, A.-C. (2023). Clifford Embeddings – A Generalized Approach for Embedding in Normed Algebras. <i>ECML-PKDD</i>. European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases, Torino.","bibtex":"@article{Demir_Ngonga Ngomo_2023, title={Clifford Embeddings – A Generalized Approach for Embedding in Normed Algebras}, journal={ECML-PKDD}, author={Demir, Caglar and Ngonga Ngomo, Axel-Cyrille}, year={2023} }","mla":"Demir, Caglar, and Axel-Cyrille Ngonga Ngomo. “Clifford Embeddings – A Generalized Approach for Embedding in Normed Algebras.” <i>ECML-PKDD</i>, 2023.","short":"C. Demir, A.-C. Ngonga Ngomo, ECML-PKDD (2023).","ama":"Demir C, Ngonga Ngomo A-C. Clifford Embeddings – A Generalized Approach for Embedding in Normed Algebras. <i>ECML-PKDD</i>. Published online 2023.","chicago":"Demir, Caglar, and Axel-Cyrille Ngonga Ngomo. “Clifford Embeddings – A Generalized Approach for Embedding in Normed Algebras.” <i>ECML-PKDD</i>, 2023.","ieee":"C. Demir and A.-C. Ngonga Ngomo, “Clifford Embeddings – A Generalized Approach for Embedding in Normed Algebras,” <i>ECML-PKDD</i>, 2023."},"has_accepted_license":"1","title":"Clifford Embeddings – A Generalized Approach for Embedding in Normed Algebras","conference":{"name":"European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases","location":"Torino"},"oa":"1","date_updated":"2023-08-01T09:22:40Z","date_created":"2023-08-01T09:12:06Z","author":[{"id":"43817","full_name":"Demir, Caglar","last_name":"Demir","first_name":"Caglar"},{"full_name":"Ngonga Ngomo, Axel-Cyrille","last_name":"Ngonga Ngomo","first_name":"Axel-Cyrille"}],"file":[{"file_id":"46244","file_name":"public.pdf","access_level":"open_access","file_size":408352,"creator":"cdemir","date_created":"2023-08-01T09:11:59Z","date_updated":"2023-08-01T09:11:59Z","relation":"main_file","content_type":"application/pdf"}],"status":"public","type":"journal_article","publication":"ECML-PKDD","ddc":["000"],"language":[{"iso":"eng"}],"file_date_updated":"2023-08-01T09:11:59Z","project":[{"name":"ENEXA: Efficient Explainable Learning on Knowledge Graphs","_id":"407","grant_number":"101070305"},{"_id":"410","name":"KnowGraphs: KnowGraphs: Knowledge Graphs at Scale"},{"_id":"285","name":"SAIL: SAIL: SustAInable Life-cycle of Intelligent Socio-Technical Systems","grant_number":"NW21-059D"}],"_id":"46243","user_id":"43817"},{"language":[{"iso":"eng"}],"file_date_updated":"2023-08-01T09:30:35Z","ddc":["000"],"department":[{"_id":"574"}],"user_id":"43817","_id":"46251","project":[{"grant_number":"101070305","_id":"407","name":"ENEXA: Efficient Explainable Learning on Knowledge Graphs"},{"name":"KnowGraphs: KnowGraphs: Knowledge Graphs at Scale","_id":"410"},{"grant_number":"NW21-059D","_id":"285","name":"SAIL: SAIL: SustAInable Life-cycle of Intelligent Socio-Technical Systems"}],"status":"public","file":[{"date_updated":"2023-08-01T09:30:35Z","creator":"cdemir","date_created":"2023-08-01T09:30:35Z","file_size":340865,"file_id":"46252","file_name":"public.pdf","access_level":"open_access","content_type":"application/pdf","relation":"main_file"}],"publication":"International Joint Conference on Artificial Intelligence","type":"journal_article","conference":{"name":"International Joint Conference on Artificial Intelligence IJCAI 2023","location":"Macau"},"title":"Neuro-Symbolic Class Expression Learning","author":[{"first_name":"Caglar","id":"43817","full_name":"Demir, Caglar","last_name":"Demir"},{"last_name":"Ngonga Ngomo","full_name":"Ngonga Ngomo, Axel-Cyrille","first_name":"Axel-Cyrille"}],"date_created":"2023-08-01T09:30:37Z","date_updated":"2023-08-01T09:44:30Z","oa":"1","citation":{"apa":"Demir, C., &#38; Ngonga Ngomo, A.-C. (2023). Neuro-Symbolic Class Expression Learning. <i>International Joint Conference on Artificial Intelligence</i>. International Joint Conference on Artificial Intelligence IJCAI 2023, Macau.","bibtex":"@article{Demir_Ngonga Ngomo_2023, title={Neuro-Symbolic Class Expression Learning}, journal={International Joint Conference on Artificial Intelligence}, author={Demir, Caglar and Ngonga Ngomo, Axel-Cyrille}, year={2023} }","short":"C. Demir, A.-C. Ngonga Ngomo, International Joint Conference on Artificial Intelligence (2023).","mla":"Demir, Caglar, and Axel-Cyrille Ngonga Ngomo. “Neuro-Symbolic Class Expression Learning.” <i>International Joint Conference on Artificial Intelligence</i>, 2023.","ieee":"C. Demir and A.-C. Ngonga Ngomo, “Neuro-Symbolic Class Expression Learning,” <i>International Joint Conference on Artificial Intelligence</i>, 2023.","chicago":"Demir, Caglar, and Axel-Cyrille Ngonga Ngomo. “Neuro-Symbolic Class Expression Learning.” <i>International Joint Conference on Artificial Intelligence</i>, 2023.","ama":"Demir C, Ngonga Ngomo A-C. Neuro-Symbolic Class Expression Learning. <i>International Joint Conference on Artificial Intelligence</i>. Published online 2023."},"year":"2023","has_accepted_license":"1"},{"date_updated":"2025-09-11T09:37:16Z","author":[{"first_name":"Umair","full_name":"Qudus, Umair","id":"83392","last_name":"Qudus","orcid":"0000-0001-6714-8729"},{"orcid":"https://orcid.org/0000-0002-8609-8277","last_name":"Röder","id":"67199","full_name":"Röder, Michael","first_name":"Michael"},{"first_name":"Muhammad","full_name":"Saleem, Muhammad","last_name":"Saleem"},{"first_name":"Axel-Cyrille","id":"65716","full_name":"Ngonga Ngomo, Axel-Cyrille","last_name":"Ngonga Ngomo"}],"conference":{"location":"Hanghzou, China","end_date":"2022-10-27","start_date":"2022-10-23","name":"International Semantic Web Conference (ISWC)"},"doi":"10.1007/978-3-031-19433-7_27","publication_identifier":{"isbn":["978-3-031-19433-7"]},"has_accepted_license":"1","publication_status":"accepted","place":"Cham","page":"462--480","citation":{"ama":"Qudus U, Röder M, Saleem M, Ngonga Ngomo A-C. HybridFC: A Hybrid Fact-Checking Approach for Knowledge Graphs. In: Sattler U, Hogan A, Keet M, Presutti V, eds. <i>The Semantic Web -- ISWC 2022</i>. Springer International Publishing; :462--480. doi:<a href=\"https://doi.org/10.1007/978-3-031-19433-7_27\">10.1007/978-3-031-19433-7_27</a>","ieee":"U. Qudus, M. Röder, M. Saleem, and A.-C. Ngonga Ngomo, “HybridFC: A Hybrid Fact-Checking Approach for Knowledge Graphs,” in <i>The Semantic Web -- ISWC 2022</i>, Hanghzou, China, pp. 462--480, doi: <a href=\"https://doi.org/10.1007/978-3-031-19433-7_27\">10.1007/978-3-031-19433-7_27</a>.","chicago":"Qudus, Umair, Michael Röder, Muhammad Saleem, and Axel-Cyrille Ngonga Ngomo. “HybridFC: A Hybrid Fact-Checking Approach for Knowledge Graphs.” In <i>The Semantic Web -- ISWC 2022</i>, edited by Ulrike Sattler, Aidan Hogan, Maria Keet, and Valentina Presutti, 462--480. Cham: Springer International Publishing, n.d. <a href=\"https://doi.org/10.1007/978-3-031-19433-7_27\">https://doi.org/10.1007/978-3-031-19433-7_27</a>.","apa":"Qudus, U., Röder, M., Saleem, M., &#38; Ngonga Ngomo, A.-C. (n.d.). HybridFC: A Hybrid Fact-Checking Approach for Knowledge Graphs. In U. Sattler, A. Hogan, M. Keet, &#38; V. Presutti (Eds.), <i>The Semantic Web -- ISWC 2022</i> (pp. 462--480). Springer International Publishing. <a href=\"https://doi.org/10.1007/978-3-031-19433-7_27\">https://doi.org/10.1007/978-3-031-19433-7_27</a>","mla":"Qudus, Umair, et al. “HybridFC: A Hybrid Fact-Checking Approach for Knowledge Graphs.” <i>The Semantic Web -- ISWC 2022</i>, edited by Ulrike Sattler et al., Springer International Publishing, pp. 462--480, doi:<a href=\"https://doi.org/10.1007/978-3-031-19433-7_27\">10.1007/978-3-031-19433-7_27</a>.","short":"U. Qudus, M. Röder, M. Saleem, A.-C. Ngonga Ngomo, in: U. Sattler, A. Hogan, M. Keet, V. Presutti (Eds.), The Semantic Web -- ISWC 2022, Springer International Publishing, Cham, n.d., pp. 462--480.","bibtex":"@inproceedings{Qudus_Röder_Saleem_Ngonga Ngomo, place={Cham}, title={HybridFC: A Hybrid Fact-Checking Approach for Knowledge Graphs}, DOI={<a href=\"https://doi.org/10.1007/978-3-031-19433-7_27\">10.1007/978-3-031-19433-7_27</a>}, booktitle={The Semantic Web -- ISWC 2022}, publisher={Springer International Publishing}, author={Qudus, Umair and Röder, Michael and Saleem, Muhammad and Ngonga Ngomo, Axel-Cyrille}, editor={Sattler, Ulrike and Hogan, Aidan and Keet, Maria and Presutti, Valentina}, pages={462--480} }"},"_id":"32509","project":[{"name":"KnowGraphs: KnowGraphs: Knowledge Graphs at Scale","_id":"410"}],"department":[{"_id":"34"}],"user_id":"83392","file_date_updated":"2022-12-22T15:45:29Z","popular_science":"1","type":"conference","editor":[{"first_name":"Ulrike","full_name":"Sattler, Ulrike","last_name":"Sattler"},{"full_name":"Hogan, Aidan","last_name":"Hogan","first_name":"Aidan"},{"first_name":"Maria","full_name":"Keet, Maria","last_name":"Keet"},{"first_name":"Valentina","full_name":"Presutti, Valentina","last_name":"Presutti"}],"status":"public","publisher":"Springer International Publishing","date_created":"2022-08-02T11:56:03Z","title":"HybridFC: A Hybrid Fact-Checking Approach for Knowledge Graphs","quality_controlled":"1","year":"2022","keyword":["fact checking · ensemble learning · knowledge graph veracit"],"ddc":["000"],"language":[{"iso":"eng"}],"publication":"The Semantic Web -- ISWC 2022","abstract":[{"lang":"eng","text":" We consider fact-checking approaches that aim to predict the veracity of assertions in knowledge graphs. Five main categories of fact-checking approaches for knowledge graphs have been proposed in the recent literature, of\r\nwhich each is subject to partially overlapping limitations. In particular, current text-based approaches are limited by manual feature engineering. Path-based and rule-based approaches are limited by their exclusive use of knowledge graphs as background knowledge, and embedding-based approaches suffer from low accuracy scores on current fact-checking tasks. We propose a hybrid approach—dubbed HybridFC—that exploits the diversity of existing categories of fact-checking approaches within an ensemble learning setting to achieve a significantly better prediction performance. In particular, our approach outperforms the state of the art by 0.14 to 0.27 in terms of Area Under the Receiver Operating Characteristic curve on the FactBench dataset. Our code is open-source and can be found at https://github.com/dice-group/HybridFC."}],"file":[{"file_id":"34853","file_name":"hybrid_fact_check_iswc2022.pdf","access_level":"closed","file_size":296218,"creator":"uqudus","date_created":"2022-12-22T15:45:29Z","date_updated":"2022-12-22T15:45:29Z","relation":"main_file","success":1,"content_type":"application/pdf"}]},{"ddc":["000"],"keyword":["SPARQL","benchmarking","cost-based","cost-free","federated","querying"],"language":[{"iso":"eng"}],"publication":"Semantic Web","abstract":[{"lang":"eng","text":"Finding a good query plan is key to the optimization of query runtime. This holds in particular for cost-based federation\r\nengines, which make use of cardinality estimations to achieve this goal. A number of studies compare SPARQL federation engines across different performance metrics, including query runtime, result set completeness and correctness, number of sources selected and number of requests sent. Albeit informative, these metrics are generic and unable to quantify and evaluate the accuracy of the cardinality estimators of cost-based federation engines. To thoroughly evaluate cost-based federation engines, the effect of estimated cardinality errors on the overall query runtime performance must be measured. In this paper, we address this challenge by presenting novel evaluation metrics targeted at a fine-grained benchmarking of cost-based federated SPARQL query engines. We evaluate five cost-based federated SPARQL query engines using existing as well as novel evaluation metrics by using LargeRDFBench queries. Our results provide a detailed analysis of the experimental outcomes that reveal novel insights, useful for the development of future cost-based federated SPARQL query processing engines."}],"file":[{"content_type":"application/pdf","relation":"main_file","success":1,"creator":"uqudus","date_created":"2024-01-13T11:35:53Z","date_updated":"2024-01-13T11:35:53Z","file_id":"50483","access_level":"closed","file_name":"swj2604.pdf","file_size":978478}],"publisher":"ISO Press","date_created":"2021-10-01T06:52:52Z","title":"An Empirical Evaluation of Cost-based Federated SPARQL Query Processing Engines","issue":"6","year":"2021","project":[{"name":"KnowGraphs: KnowGraphs: Knowledge Graphs at Scale","_id":"410"}],"_id":"25212","user_id":"83392","department":[{"_id":"574"}],"article_type":"original","file_date_updated":"2024-01-13T11:35:53Z","type":"journal_article","status":"public","date_updated":"2025-09-11T09:50:14Z","author":[{"orcid":"0000-0001-6714-8729","last_name":"Qudus","id":"83392","full_name":"Qudus, Umair","first_name":"Umair"},{"first_name":"Muhammad","full_name":"Saleem, Muhammad","last_name":"Saleem"},{"first_name":"Axel-Cyrille","last_name":"Ngonga Ngomo","full_name":"Ngonga Ngomo, Axel-Cyrille","id":"65716"},{"first_name":"Young-Koo","last_name":"Lee","full_name":"Lee, Young-Koo"}],"volume":12,"doi":"10.3233/SW-200420","publication_status":"accepted","publication_identifier":{"issn":["2210-4968"]},"has_accepted_license":"1","citation":{"ama":"Qudus U, Saleem M, Ngonga Ngomo A-C, Lee Y-K. An Empirical Evaluation of Cost-based Federated SPARQL Query Processing Engines. <i>Semantic Web</i>. 12(6):843-868. doi:<a href=\"https://doi.org/10.3233/SW-200420\">10.3233/SW-200420</a>","ieee":"U. Qudus, M. Saleem, A.-C. Ngonga Ngomo, and Y.-K. Lee, “An Empirical Evaluation of Cost-based Federated SPARQL Query Processing Engines,” <i>Semantic Web</i>, vol. 12, no. 6, pp. 843–868, doi: <a href=\"https://doi.org/10.3233/SW-200420\">10.3233/SW-200420</a>.","chicago":"Qudus, Umair, Muhammad Saleem, Axel-Cyrille Ngonga Ngomo, and Young-Koo Lee. “An Empirical Evaluation of Cost-Based Federated SPARQL Query Processing Engines.” <i>Semantic Web</i> 12, no. 6 (n.d.): 843–68. <a href=\"https://doi.org/10.3233/SW-200420\">https://doi.org/10.3233/SW-200420</a>.","short":"U. Qudus, M. Saleem, A.-C. Ngonga Ngomo, Y.-K. Lee, Semantic Web 12 (n.d.) 843–868.","bibtex":"@article{Qudus_Saleem_Ngonga Ngomo_Lee, title={An Empirical Evaluation of Cost-based Federated SPARQL Query Processing Engines}, volume={12}, DOI={<a href=\"https://doi.org/10.3233/SW-200420\">10.3233/SW-200420</a>}, number={6}, journal={Semantic Web}, publisher={ISO Press}, author={Qudus, Umair and Saleem, Muhammad and Ngonga Ngomo, Axel-Cyrille and Lee, Young-Koo}, pages={843–868} }","mla":"Qudus, Umair, et al. “An Empirical Evaluation of Cost-Based Federated SPARQL Query Processing Engines.” <i>Semantic Web</i>, vol. 12, no. 6, ISO Press, pp. 843–68, doi:<a href=\"https://doi.org/10.3233/SW-200420\">10.3233/SW-200420</a>.","apa":"Qudus, U., Saleem, M., Ngonga Ngomo, A.-C., &#38; Lee, Y.-K. (n.d.). An Empirical Evaluation of Cost-based Federated SPARQL Query Processing Engines. <i>Semantic Web</i>, <i>12</i>(6), 843–868. <a href=\"https://doi.org/10.3233/SW-200420\">https://doi.org/10.3233/SW-200420</a>"},"page":"843-868","intvolume":"        12"}]