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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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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
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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
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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
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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
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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
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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
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(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
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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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