Johannes Fürnkranz


2019

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Learning Analogy-Preserving Sentence Embeddings for Answer Selection
Aïssatou Diallo | Markus Zopf | Johannes Fürnkranz
Proceedings of the 23rd Conference on Computational Natural Language Learning (CoNLL)

Answer selection aims at identifying the correct answer for a given question from a set of potentially correct answers. Contrary to previous works, which typically focus on the semantic similarity between a question and its answer, our hypothesis is that question-answer pairs are often in analogical relation to each other. Using analogical inference as our use case, we propose a framework and a neural network architecture for learning dedicated sentence embeddings that preserve analogical properties in the semantic space. We evaluate the proposed method on benchmark datasets for answer selection and demonstrate that our sentence embeddings indeed capture analogical properties better than conventional embeddings, and that analogy-based question answering outperforms a comparable similarity-based technique.

2018

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Which Scores to Predict in Sentence Regression for Text Summarization?
Markus Zopf | Eneldo Loza Mencía | Johannes Fürnkranz
Proceedings of the 2018 Conference of the North American Chapter of the Association for Computational Linguistics: Human Language Technologies, Volume 1 (Long Papers)

The task of automatic text summarization is to generate a short text that summarizes the most important information in a given set of documents. Sentence regression is an emerging branch in automatic text summarizations. Its key idea is to estimate the importance of information via learned utility scores for individual sentences. These scores are then used for selecting sentences from the source documents, typically according to a greedy selection strategy. Recently proposed state-of-the-art models learn to predict ROUGE recall scores of individual sentences, which seems reasonable since the final summaries are evaluated according to ROUGE recall. In this paper, we show in extensive experiments that following this intuition leads to suboptimal results and that learning to predict ROUGE precision scores leads to better results. The crucial difference is to aim not at covering as much information as possible but at wasting as little space as possible in every greedy step.

2016

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Beyond Centrality and Structural Features: Learning Information Importance for Text Summarization
Markus Zopf | Eneldo Loza Mencía | Johannes Fürnkranz
Proceedings of The 20th SIGNLL Conference on Computational Natural Language Learning

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Sequential Clustering and Contextual Importance Measures for Incremental Update Summarization
Markus Zopf | Eneldo Loza Mencía | Johannes Fürnkranz
Proceedings of COLING 2016, the 26th International Conference on Computational Linguistics: Technical Papers

Unexpected events such as accidents, natural disasters and terrorist attacks represent an information situation where it is crucial to give users access to important and non-redundant information as early as possible. Incremental update summarization (IUS) aims at summarizing events which develop over time. In this paper, we propose a combination of sequential clustering and contextual importance measures to identify important sentences in a stream of documents in a timely manner. Sequential clustering is used to cluster similar sentences. The created clusters are scored by a contextual importance measure which identifies important information as well as redundant information. Experiments on the TREC Temporal Summarization 2015 shared task dataset show that our system achieves superior results compared to the best participating systems.

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What Makes Word-level Neural Machine Translation Hard: A Case Study on English-German Translation
Fabian Hirschmann | Jinseok Nam | Johannes Fürnkranz
Proceedings of COLING 2016, the 26th International Conference on Computational Linguistics: Technical Papers

Traditional machine translation systems often require heavy feature engineering and the combination of multiple techniques for solving different subproblems. In recent years, several end-to-end learning architectures based on recurrent neural networks have been proposed. Unlike traditional systems, Neural Machine Translation (NMT) systems learn the parameters of the model and require only minimal preprocessing. Memory and time constraints allow to take only a fixed number of words into account, which leads to the out-of-vocabulary (OOV) problem. In this work, we analyze why the OOV problem arises and why it is considered a serious problem in German. We study the effectiveness of compound word splitters for alleviating the OOV problem, resulting in a 2.5+ BLEU points improvement over a baseline on the WMT’14 German-to-English translation task. For English-to-German translation, we use target-side compound splitting through a special syntax during training that allows the model to merge compound words and gain 0.2 BLEU points.