167 research outputs found

    Robust Grammatical Analysis for Spoken Dialogue Systems

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    We argue that grammatical analysis is a viable alternative to concept spotting for processing spoken input in a practical spoken dialogue system. We discuss the structure of the grammar, and a model for robust parsing which combines linguistic sources of information and statistical sources of information. We discuss test results suggesting that grammatical processing allows fast and accurate processing of spoken input.Comment: Accepted for JNL

    Evaluation of the NLP Components of the OVIS2 Spoken Dialogue System

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    The NWO Priority Programme Language and Speech Technology is a 5-year research programme aiming at the development of spoken language information systems. In the Programme, two alternative natural language processing (NLP) modules are developed in parallel: a grammar-based (conventional, rule-based) module and a data-oriented (memory-based, stochastic, DOP) module. In order to compare the NLP modules, a formal evaluation has been carried out three years after the start of the Programme. This paper describes the evaluation procedure and the evaluation results. The grammar-based component performs much better than the data-oriented one in this comparison.Comment: Proceedings of CLIN 9

    From Monologue to Dialogue: Natural Language Generation in OVIS

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    This paper describes how a language generation system that was originally designed for monologue generation, has been adapted for use in the OVIS spoken dialogue system. To meet the requirement that in a dialogue, the system's utterances should make up a single, coherent dialogue turn, several modifications had to be made to the system. The paper also discusses the influence of dialogue context on information status, and its consequences for the generation of referring expressions and accentuation

    Extracting Information from Spoken User Input:A Machine Learning Approach

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    We propose a module that performs automatic analysis of user input in spoken dialogue systems using machine learning algorithms. The input to the module is material received from the speech recogniser and the dialogue manager of the spoken dialogue system, the output is a four-level pragmatic-semantic representation of the user utterance. Our investigation shows that when the four interpretation levels are combined in a complex machine learning task, the performance of the module is significantly better than the score of an informed baseline strategy. However, via a systematic, automatised search for the optimal subtask combinations we can gain substantial improvement produced by both classifiers for all four interpretation subtasks. A case study is conducted on dialogues between an automatised, experimental system that gives information on the phone about train connections in the Netherlands, and its users who speak in Dutch. We find that drawing on unsophisticated, potentially noisy features that characterise the dialogue situation, and by performing automatic optimisation of the formulated machine learning task it is possible to extract sophisticated information of practical pragmatic-semantic value from spoken user input with robust performance. This means that our module can with a good score interpret whether the user of the system is giving slot-filling information, and for which query slots (e.g., departure station, departure time, etc.), whether the user gave a positive or a negative answer to the system, or whether the user signals that there are problems in the interaction.

    Learning Efficient Disambiguation

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    This dissertation analyses the computational properties of current performance-models of natural language parsing, in particular Data Oriented Parsing (DOP), points out some of their major shortcomings and suggests suitable solutions. It provides proofs that various problems of probabilistic disambiguation are NP-Complete under instances of these performance-models, and it argues that none of these models accounts for attractive efficiency properties of human language processing in limited domains, e.g. that frequent inputs are usually processed faster than infrequent ones. The central hypothesis of this dissertation is that these shortcomings can be eliminated by specializing the performance-models to the limited domains. The dissertation addresses "grammar and model specialization" and presents a new framework, the Ambiguity-Reduction Specialization (ARS) framework, that formulates the necessary and sufficient conditions for successful specialization. The framework is instantiated into specialization algorithms and applied to specializing DOP. Novelties of these learning algorithms are 1) they limit the hypotheses-space to include only "safe" models, 2) are expressed as constrained optimization formulae that minimize the entropy of the training tree-bank given the specialized grammar, under the constraint that the size of the specialized model does not exceed a predefined maximum, and 3) they enable integrating the specialized model with the original one in a complementary manner. The dissertation provides experiments with initial implementations and compares the resulting Specialized DOP (SDOP) models to the original DOP models with encouraging results.Comment: 222 page

    The Use of Story Reading as a Method of Improving Verbal Expression of Head Start Children

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    The purpose of this experimental study was to conduct and evaluate a teaching method for improving verbal expression performance of Head Start children. The teaching method of language stimulation given the experimental subjects was based on story reading and retelling with active participation by the children in daily small group tutoring sessions, for seven weeks. An academic program given the control subjects included specific vocabulary and sequencing training. Verbal expression was measured by an analysis of stories told by each subject before and after tutoring, in response to sequence pictures and standup figures. Measures of vocabulary, sentence structure and evidence of sequence were used in the analysis. The experimental language tutored group gained significantly from pre- to posttest in 11 Of 20 verbal expression criteria. Although a comparison of group means showed the experimental group\u27s performance to have exceeded that of the control group in 15 criteria, only one vocabulary score was significantly greater for the experimental subjects. It was concluded that verbal expression skills can be accelerated through training. The teaching method based on story reading was recommended for use by Odgen Head Start teachers as one method of improving verbal expression

    Computational linguistics in the Netherlands 1996 : papers from the 7th CLIN meeting, November 15, 1996, Eindhoven

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