Abstract

NEVěřILOVA, Zuzana. Paraphrase and Textual Entailment Generation in Czech. Comp. y Sist. [online]. 2014, vol.18, n.3, pp.555-568. ISSN 2007-9737.  https://doi.org/10.13053/CyS-18-3-2040.

Paraphrase and textual entailment generation can support natural language processing (NLP) tasks that simulate text understanding, e.g., text summarization, plagiarism detection, or question answering. A paraphrase, i.e., a sentence with the same meaning, conveys a certain piece of information with new words and new syntactic structures. Textual entailment, i.e., an inference that humans will judge most likely true, can employ real-world knowledge in order to make some implicit information explicit. Paraphrases can also be seen as mutual entailments. We present a new system that generates paraphrases and textual entailments from a given text in the Czech language. First, the process is rule-based, i.e., the system analyzes the input text, produces its inner representation, transforms it according to transformation rules, and generates new sentences. Second, the generated sentences are ranked according to a statistical model and only the best ones are output. The decision whether a paraphrase or textual entailment is correct or not is left to humans. For this purpose we designed an annotation game based on a conversation between a detective (the human player) and his assistant (the system). The result of such annotation is a collection of annotated pairs text-hypothesis. Currently, the system and the game are intended to collect data in the Czech language. However, the idea can be applied for other languages. So far, we have collected 3,321 H-T pairs. From these pairs, 1,563 were judged correct (47.06 %), 1,238 (37.28 %) were judged incorrect entailments, and 520 (15.66 %) were judged non-sense or unknown.

Keywords : Games with a purpose; paraphrase; textual entailment; natural language generation.

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