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30 March – 8 April 2005 Dipartimento di Informatica, Universita di Pisa ML for NLP With Special Focus on Tagging and Parsing Kiril Ribarov.

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Presentation on theme: "30 March – 8 April 2005 Dipartimento di Informatica, Universita di Pisa ML for NLP With Special Focus on Tagging and Parsing Kiril Ribarov."— Presentation transcript:

1 30 March – 8 April 2005 Dipartimento di Informatica, Universita di Pisa ML for NLP With Special Focus on Tagging and Parsing Kiril Ribarov

2 Lecture structure Machine learning in general T.M. Mitchell, Machine Learning (1997, McGraw- Hill): hypothesis, decision trees, ANN, computational learning theory, instance-based learning, genetic algorithms, (Bayesian learning), [case-based, analytical learning] Natural Language – linguistically Natural Language – computationally and stochastically

3 Lecture structure – cont. The Prague Dependency Treebank – data and tools Morphological Tagging  Bayesian Learning (HMM, smoothing, EM, Maximum Entropy, related issues as Viterbi search, Lagrange multipliers)  Rule-Based Approach  Perceptron-Based Approach  Tagset structure, tagset size  Morphological contexts

4 Lecture structure – cont. Parsing  The problem of parsing, dependency parsing  Statistical parsing  Rule-Based parsing  Language graphs and sentence graphs  Naïve parsing  Rule-Based revisited  Perceptron-Based parsing

5 Lecture structure – cont. Parsing by tagging and tagging by parsing  Morphological contexts, tree contexts  G-tags, tagging by g-tags  Alignment of g-tags and m-tags Some problem definitions

6 We will include as well Problems of evaluation and its measurement for tagging and for parsing Specialties of dependency trees, surface and deep syntax, projectivity and non-projectivity Current trials on high-quality MT Ongoing research on valencies

7 Our aim To present general ML techniques To present the Prague Dependency Treebank To present NLP specific approaches, their modifications, applications (medium: PDT) To present mistakes and successes To present the newest ideas developed for automatic dependency acquisition To raise questions and thus indicate new directions for research in NLP

8 (Restriction) to Tagging and Parsing Tagging and parsing as the two most important NLP modules for various application domains. Tagging and parsing undoubtedly improve: grammar checking, speech processing, information retrieval, machine translation, … Each of the applications does not necessarily use the same tagging/parsing outputs; modifications are introduced to serve best the specific application Each of the applications has its specific core modules different than tagging/parsing Many technicalities in these are approaches are nevertheless similar

9 Machine Learning in General T.M. Mitchell, Machine Learning (1997, McGraw- Hill): hypothesis, decision trees, ANN, computational learning theory, instance-based learning, genetic algorithms


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