September 27, 2018

Ömer Kırnap, M.S. 2018

Current Position: Applied Scientist II, Amazon, San Francisco (personal website, LinkedIn)
M.S Thesis: Transition Based Dependency Parsing with Deep Learning, Koç University, Department of Computer Engineering. September 2018. (PDF, Presentation).
Publications: CoNLL18 and CoNLL17
Code: CoNLL18 and CoNLL17

Thesis Abstract:
I introduce word and context embeddings derived from a language model representing left/right context of a word instance and demonstrate that context embeddings significantly improve the accuracy of transition based parser. Our multi-layer perceptron (MLP) parser making use of these embeddings was ranked 7th out of 33 participants (ranked 1st among transition based parsers) in CoNLL 2017 UD Shared Task. However MLP parser relies on additional hand-crafted features which are used to summarize sequential information. I exploit recurrent neural networks to remove these features by implementing tree-stack LSTM, and develop new set of continuous embeddings called morphological feature embeddings. According to official comparison results in CoNLL 2018 UD Shared Task, our tree-stack LSTM outperforms MLP in transition based dependency parsing.


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July 02, 2018

July 01, 2018

Morphological Disambiguation for Turkish

Dilek Zeynep Hakkani-Tür, Murat Saraçlar, Gökhan Tür, Kemal Oflazer and Deniz Yuret. 2018. In Turkish Natural Language Processing, Kemal Oflazer and Murat Saraçlar (Eds.), Ch.3, pp.53-68. Springer. (URL)

Abstract: Morphological disambiguation is the task of determining the contextually correct morphological parses of tokens in a sentence. A morphological disambiguator takes in sets of morphological parses for each token, generated by a morphological analyzer, and then selects a morphological parse for each, considering statistical and/or linguistic contextual information. This task can be seen as a generalization of the part-of-speech (POS) tagging problem for morphologically rich languages. The disambiguated morphological analysis is usually crucial for further processing steps such as dependency parsing. In this chapter, we review morphological disambiguation problem for Turkish and discuss approaches for solving this problem as they have evolved from manually crafted constraint-based rule systems to systems employing machine learning.


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