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收集所有交通大學研究人員與學生個人或團體所發表之各項學術著作,涵蓋期刊論文、教師專書、學位論文等項。;;Collections of Publications of NCTU Researchers and Students Like Journal Papers and Thesis.
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Item type:Item, Hierarchical Pitman-Yor and Dirichlet Process for Language Model(2013-01-01) ;Chien, Jen-Tzung ;Chang, Ying-Lan ;電機工程學系Department of Electrical and Computer EngineeringThis paper presents a nonparametric interpretation for modem language model based on the hierarchical Pitman-Yor and Dirichlet (HPYD) process. We propose the HPYD language model (HPYD-LM) which flexibly conducts backoff smoothing and topic clustering through Bayesian nonparametric learning. The nonparametric priors of backoff n-grams and latent topics are tightly coupled in a compound process. A hybrid probability measure is drawn to build the smoothed topic-based LM. The model structure is automatically determined from training data. A new Chinese restaurant scenario is proposed to implement HPYD-LM via Gibbs sampling. This process reflects the power-law property and extracts the semantic topics from natural language. The superiority of HPYD-LM to the related LMs is demonstrated by the experiments on different corpora in terms of perplexity and word error rate.Item type:Item, BAYESIAN NONPARAMETRIC LANGUAGE MODELS(2012) ;Chang, Ying-Lan ;Chien, Jen-Tzung ;電機資訊學士班Undergraduate Honors Program of Electrical Engineering and Computer ScienceBackoff smoothing and topic modeling are crucial issues in n-gram language model. This paper presents a Bayesian non-parametric learning approach to tackle these two issues. We develop a topic-based language model where the numbers of topics and n-grams are automatically determined from data. To cope with this model selection problem, we introduce the nonparametric priors for topics and backoff n-grams. The infinite language models are constructed through the hierarchical Dirichlet process compound Pitman-Yor (PY) process. We develop the topic-based hierarchical PY language model (THPY-LM) with power-law behavior. This model can be simplified to the hierarchical PY (HPY) LM by disregarding the topic information and also the modified Kneser-Ney (MKN) LM by further disregarding the Bayesian treatment. In the experiments, the proposed THPY-LM outperforms state-of-art methods using MKN-LM and HPY-LM.