Axel-Cyrille Ngonga Ngomo


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CausalQA: A Benchmark for Causal Question Answering
Alexander Bondarenko | Magdalena Wolska | Stefan Heindorf | Lukas Blübaum | Axel-Cyrille Ngonga Ngomo | Benno Stein | Pavel Braslavski | Matthias Hagen | Martin Potthast
Proceedings of the 29th International Conference on Computational Linguistics

At least 5% of questions submitted to search engines ask about cause-effect relationships in some way. To support the development of tailored approaches that can answer such questions, we construct Webis-CausalQA-22, a benchmark corpus of 1.1 million causal questions with answers. We distinguish different types of causal questions using a novel typology derived from a data-driven, manual analysis of questions from ten large question answering (QA) datasets. Using high-precision lexical rules, we extract causal questions of each type from these datasets to create our corpus. As an initial baseline, the state-of-the-art QA model UnifiedQA achieves a ROUGE-L F1 score of 0.48 on our new benchmark.


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A General Benchmarking Framework for Text Generation
Diego Moussallem | Paramjot Kaur | Thiago Ferreira | Chris van der Lee | Anastasia Shimorina | Felix Conrads | Michael Röder | René Speck | Claire Gardent | Simon Mille | Nikolai Ilinykh | Axel-Cyrille Ngonga Ngomo
Proceedings of the 3rd International Workshop on Natural Language Generation from the Semantic Web (WebNLG+)

The RDF-to-text task has recently gained substantial attention due to the continuous growth of RDF knowledge graphs in number and size. Recent studies have focused on systematically comparing RDF-to-text approaches on benchmarking datasets such as WebNLG. Although some evaluation tools have already been proposed for text generation, none of the existing solutions abides by the Findability, Accessibility, Interoperability, and Reusability (FAIR) principles and involves RDF data for the knowledge extraction task. In this paper, we present BENG, a FAIR benchmarking platform for Natural Language Generation (NLG) and Knowledge Extraction systems with focus on RDF data. BENG builds upon the successful benchmarking platform GERBIL, is opensource and is publicly available along with the data it contains.


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A Holistic Natural Language Generation Framework for the Semantic Web
Axel-Cyrille Ngonga Ngomo | Diego Moussallem | Lorenz Bühmann
Proceedings of the International Conference on Recent Advances in Natural Language Processing (RANLP 2019)

With the ever-growing generation of data for the Semantic Web comes an increasing demand for this data to be made available to non-semantic Web experts. One way of achieving this goal is to translate the languages of the Semantic Web into natural language. We present LD2NL, a framework that allows verbalizing the three key languages of the Semantic Web, i.e., RDF, OWL, and SPARQL. Our framework is based on a bottom-up approach to verbalization. We evaluated LD2NL in an open survey with 86 persons. Our results suggest that our framework can generate verbalizations that are close to natural languages and that can be easily understood by non-experts. Therewith, it enables non-domain experts to interpret Semantic Web data with more than 91% of the accuracy of domain experts.


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BENGAL: An Automatic Benchmark Generator for Entity Recognition and Linking
Axel-Cyrille Ngonga Ngomo | Michael Röder | Diego Moussallem | Ricardo Usbeck | René Speck
Proceedings of the 11th International Conference on Natural Language Generation

The manual creation of gold standards for named entity recognition and entity linking is time- and resource-intensive. Moreover, recent works show that such gold standards contain a large proportion of mistakes in addition to being difficult to maintain. We hence present Bengal, a novel automatic generation of such gold standards as a complement to manually created benchmarks. The main advantage of our benchmarks is that they can be readily generated at any time. They are also cost-effective while being guaranteed to be free of annotation errors. We compare the performance of 11 tools on benchmarks in English generated by Bengal and on 16 benchmarks created manually. We show that our approach can be ported easily across languages by presenting results achieved by 4 tools on both Brazilian Portuguese and Spanish. Overall, our results suggest that our automatic benchmark generation approach can create varied benchmarks that have characteristics similar to those of existing benchmarks. Our approach is open-source. Our experimental results are available at and the code at

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LIdioms: A Multilingual Linked Idioms Data Set
Diego Moussallem | Mohamed Ahmed Sherif | Diego Esteves | Marcos Zampieri | Axel-Cyrille Ngonga Ngomo
Proceedings of the Eleventh International Conference on Language Resources and Evaluation (LREC 2018)

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RDF2PT: Generating Brazilian Portuguese Texts from RDF Data
Diego Moussallem | Thiago Ferreira | Marcos Zampieri | Maria Claudia Cavalcanti | Geraldo Xexéo | Mariana Neves | Axel-Cyrille Ngonga Ngomo
Proceedings of the Eleventh International Conference on Language Resources and Evaluation (LREC 2018)


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Proceedings of the Open Knowledge Base and Question Answering Workshop (OKBQA 2016)
Key-Sun Choi | Christina Unger | Piek Vossen | Jin-Dong Kim | Noriko Kando | Axel-Cyrille Ngonga Ngomo
Proceedings of the Open Knowledge Base and Question Answering Workshop (OKBQA 2016)


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A tool suite for creating question answering benchmarks
Axel-Cyrille Ngonga Ngomo | Norman Heino | René Speck | Prodromos Malakasiotis
Proceedings of the Ninth International Conference on Language Resources and Evaluation (LREC'14)

We introduce the BIOASQ suite, a set of open-source Web tools for the creation, assessment and community-driven improvement of question answering benchmarks. The suite comprises three main tools: (1) the annotation tool supports the creation of benchmarks per se. In particular, this tool allows a team of experts to create questions and answers as well as to annotate the latter with documents, document snippets, RDF triples and ontology concepts. While the creation of questions is supported by different views and contextual information pertaining to the same question, the creation of answers is supported by the integration of several search engines and context information to facilitate the retrieval of the said answers as well as their annotation. (2) The assessment tool allows comparing several answers to the same question. Therewith, it can be used to assess the inter-annotator agreement as well as to manually evaluate automatically generated answers. (3) The third tool in the suite, the social network, aims to ensure the sustainability and iterative improvement of the benchmark by empowering communities of experts to provide insights on the questions in the benchmark. The BIOASQ suite has already been used successfully to create the 311 questions comprised in the BIOASQ question answering benchmark. It has also been evaluated by the experts who used it to create the BIOASQ benchmark.


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EAGER: Extending Automatically Gazetteers for Entity Recognition
Omer Farukhan Gunes | Tim Furche | Christian Schallhart | Jens Lehmann | Axel-Cyrille Ngonga Ngomo
Proceedings of the 3rd Workshop on the People’s Web Meets NLP: Collaboratively Constructed Semantic Resources and their Applications to NLP