Automatic definition extraction from texts is an important task that has numerous applications in several natural language processing fields such as summarization, analysis of scientific texts, automatic taxonomy generation, ontology generation, concept identification, and question answering. For definitions that are contained within a single sentence, this problem can be viewed as a binary classification of sentences into definitions and non-definitions. In this paper, we focus on automatic detection of one-sentence definitions in mathematical texts, which are difficult to separate from surrounding text. We experiment with several data representations, which include sentence syntactic structure and word embeddings, and apply deep learning methods such as the Convolutional Neural Network (CNN) and the Long Short-Term Memory network (LSTM), in order to identify mathematical definitions. Our experiments demonstrate the superiority of CNN and its combination with LSTM, when applied on the syntactically-enriched input representation. We also present a new dataset for definition extraction from mathematical texts. We demonstrate that this dataset is beneficial for training supervised models aimed at extraction of mathematical definitions. Our experiments with different domains demonstrate that mathematical definitions require special treatment, and that using cross-domain learning is inefficient for that task.
Within the period of 1993–2014 Russia experienced four major electoral reforms: in 1993, 2002, 2005 and 2014. One further attempt to change the Russian electoral system, initiated by President Yeltsin in 1994–95, was unsuccessful. We suggest that the successes as well as the failures of the electoral reforms in Russia can be explained with the same reasons as in other countries regardless of their political regime. In our view, electoral reforms within any political system are rooted in the specific arrangement of the veto players within the system and their political preferences. This paper demonstrates that major electoral reforms were successfully implemented in cases when the executive branch headed by the Russian president, striving for maximum control over the legislative process, was interested in such implementation and there were no other veto players able to block passage of the law.
One more attempt to change the Russian electoral system initiated by the president in 1994-1995 failed. This article considers the cases of major electoral reforms in Russia through the veto player theory. It demonstrates that the reforms were successfully implemented in cases when the executive branch, striving for maximum control over the legislative process, was interested in such implementation and there were no other veto players, who were able to block passage of the law.
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