Similarity measures for semantic relation extraction

(eng) Semantic relations, such as synonyms, hypernyms and co-hyponyms proved to be useful for text processing applications, including text similarity, query expansion, question answering and word sense disambiguation. Such relations are practical because of the gap between lexical surface of the text and its meaning. Indeed, the same concept is often represented by different terms. However, existing resources often do not cover a vocabulary required by a given system. Manual resource construction is prohibitively expensive for many projects. On the other hand, precision of the existing extractors still do not meet quality of the hand-crafted resources. All these factors motivate the development of novel extraction methods. This thesis deals with similarity measures for semantic relation extraction. The main research question we address, is how to improve precision and coverage of such measures. First, we perform a large-scale study the baseline techniques. Second, we propose four novel measures. One of them significantly outperforms the baselines, the others perform comparably to the state-of-the-art techniques. Finally, we successfully apply one of the novel measures in two text processing systems.