Antti-Veikko I. Rosti

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Recently, confusion network decoding has been applied in machine translation system combination. Due to errors in the hypothesis alignment, decoding may result in un-grammatical combination outputs. This paper describes an improved confusion network based method to combine outputs from multiple MT systems. In this approach, arbitrary features may be added(More)
Currently there are several approaches to machine translation (MT) based on different paradigms; e.g., phrasal, hierarchical and syntax-based. These three approaches yield similar translation accuracy despite using fairly different levels of linguistic knowledge. The availability of such a variety of systems has led to a growing interest toward finding(More)
Current statistical machine translation (SMT) systems are trained on sentence-aligned and word-aligned parallel text collected from various sources. Translation model parameters are estimated from the word alignments, and the quality of the translations on a given test set depends on the parameter estimates. There are at least two factors affecting the(More)
Confusion network decoding has been the most successful approach in combining outputs from multiple machine translation (MT) systems in the recent DARPA GALE and NIST Open MT evaluations. Due to the varying word order between outputs from different MT systems, the hypothesis alignment presents the biggest challenge in confusion network decoding. This paper(More)
This paper describes the application of Rao-Blackwellised Gibbs sampling (RBGS) to speech recognition using switching linear dy-namical systems (SLDSs). The SLDS is a hybrid of standard hidden Markov models (HMMs) and linear dynamical systems. It is an extension of the stochastic segment model as it relaxes the assumption of independent segments. SLDSs(More)
BBN submitted system combination outputs for CzechEnglish language pairs. All combinations were based on confusion network decoding. An incremental hypothesis alignment algorithm with flexible matching was used to build the networks. The bi-gram decoding weights for the single source language translations were tuned directly to maximize the BLEU score of(More)
Preface The research and study presented in this thesis was carried out in the Signal I would like to thank Professor Visa Koivunen, my advisor and examiner, for his valuable guidance in statistical signal processing and making of this thesis. I would also like to thank my other examiner, Lic. Tech. Jukka Mannerkoski, for sharing his expertise in(More)
Recently various techniques to improve the correlation model of feature vector elements in speech recognition systems have been proposed. Such techniques include semi-tied covariance HMMs and systems based on factor analysis. All these schemes have been shown to improve the speech recognition performance without dramatically increasing the number of model(More)