94,364 research outputs found
Tree transducers, L systems, and two-way machines
A relationship between parallel rewriting systems and two-way machines is investigated. Restrictions on the âcopying powerâ of these devices endow them with rich structuring and give insight into the issues of determinism, parallelism, and copying. Among the parallel rewriting systems considered are the top-down tree transducer; the generalized syntax-directed translation scheme and the ETOL system, and among the two-way machines are the tree-walking automaton, the two-way finite-state transducer, and (generalizations of) the one-way checking stack automaton. The. relationship of these devices to macro grammars is also considered. An effort is made .to provide a systematic survey of a number of existing results
GREAT: open source software for statistical machine translation
The final publication is available at Springer via http://dx.doi.org/10.1007/s10590-011-9097-6[EN] In this article, the first public release of GREAT as an open-source, statistical machine translation (SMT) software toolkit is described. GREAT is based on a bilingual language modelling approach for SMT, which is so far implemented for n-gram models based on the framework of stochastic finite-state transducers. The use of finite-state models is motivated by their simplicity, their versatility, and the fact that they present a lower computational cost, if compared with other more expressive models. Moreover, if translation is assumed to be a subsequential process, finite-state models are enough for modelling the existing relations between a source and a target language. GREAT includes some characteristics usually present in state-of-the-art SMT, such as phrase-based translation models or a log-linear framework for local features. Experimental results on a well-known corpus such as Europarl are reported in order to validate this software. A competitive translation quality is achieved, yet using both a lower number of model parameters and a lower response time than the widely-used, state-of-the-art SMT system Moses. © 2011 Springer Science+Business Media B.V.Study was supported by the EC (FEDER, FSE), the Spanish government (MICINN, MITyC, âPlan Eâ, under Grants MIPRCV âConsolider Ingenio 2010â, iTrans2 TIN2009-14511, and erudito.com TSI-020110-2009-439), and the Generalitat Valenciana (Grant Prometeo/2009/014).GonzĂĄlez MollĂĄ, J.; Casacuberta Nolla, F. (2011). GREAT: open source software for statistical machine translation. Machine Translation. 25(2):145-160. https://doi.org/10.1007/s10590-011-9097-6S145160252Amengual JC, BenedĂ JM, Casacuberta F, Castaño MA, Castellanos A, JimĂ©nez VM, Llorens D, Marzal A, Pastor M, Prat F, Vidal E, Vilar JM (2000) The EUTRANS-I speech translation system. Mach Transl 15(1-2): 75â103AndrĂ©s-Ferrer J, Juan-CĂscar A, Casacuberta F (2008) Statistical estimation of rational transducers applied to machine translation. Appl Artif Intell 22(1â2): 4â22Bangalore S, Riccardi G (2002) Stochastic finite-state models for spoken language machine translation. Mach Transl 17(3): 165â184Berstel J (1979) Transductions and context-free languages. B.G. Teubner, Stuttgart, GermanyCasacuberta F, Vidal E (2004) Machine translation with inferred stochastic finite-state transducers. Comput Linguist 30(2): 205â225Casacuberta F, Vidal E (2007) Learning finite-state models for machine translation. Mach Learn 66(1): 69â91Foster G, Kuhn R, Johnson H (2006) Phrasetable smoothing for statistical machine translation. In: Proceedings of the 11th Conference on Empirical Methods in Natural Language Processing, Stroudsburg, PA, pp 53â61GonzĂĄlez J (2009) Aprendizaje de transductores estocĂĄsticos de estados finitos y su aplicaciĂłn en traducciĂłn automĂĄtica. PhD thesis, Universitat PolitĂšcnica de ValĂšncia. Advisor: Casacuberta FGonzĂĄlez J, Casacuberta F (2009) GREAT: a finite-state machine translation toolkit implementing a grammatical inference approach for transducer inference (GIATI). In: Proceedings of the EACL Workshop on Computational Linguistic Aspects of Grammatical Inference, Athens, Greece, pp 24â32Kanthak S, Vilar D, Matusov E, Zens R, Ney H (2005) Novel reordering approaches in phrase-based statistical machine translation. In: Proceedings of the ACL Workshop on Building and Using Parallel Texts: Data-Driven Machine Translation and Beyond, Ann Arbor, MI, pp 167â174Karttunen L (2001) Applications of finite-state transducers in natural language processing. In: Proceedings of the 5th Conference on Implementation and Application of Automata, London, UK, pp 34â46Kneser R, Ney H (1995) Improved backing-off for n-gram language modeling. 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In: Procee- dings of the ACL Workshop on Statistical Machine Translation, Morristown, NJ, pp 135â139Llorens D, Vilar JM, Casacuberta F (2002) Finite state language models smoothed using n-grams. Int J Pattern Recognit Artif Intell 16(3): 275â289Marcu D, Wong W (2002) A phrase-based, joint probability model for statistical machine translation. In: Proceedings of the 7th Conference on Empirical Methods in Natural Language Processing, Morristown, NJ, pp 133â139Mariño JB, Banchs RE, Crego JM, de Gispert A, Lambert P, Fonollosa JAR, Costa-jussĂ MR (2006) N-gram-based machine translation. Comput Linguist 32(4): 527â549Medvedev YT (1964) On the class of events representable in a finite automaton. In: Moore EF (eds) Sequential machines selected papers. Addison Wesley, Reading, MAMohri M, Pereira F, Riley M (2002) Weighted finite-state transducers in speech recognition. 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Cellular Automata as a Model of Physical Systems
Cellular Automata (CA), as they are presented in the literature, are abstract
mathematical models of computation. In this pa- per we present an alternate
approach: using the CA as a model or theory of physical systems and devices.
While this approach abstracts away all details of the underlying physical
system, it remains faithful to the fact that there is an underlying physical
reality which it describes. This imposes certain restrictions on the types of
computations a CA can physically carry out, and the resources it needs to do
so. In this paper we explore these and other consequences of our
reformalization.Comment: To appear in the Proceedings of AUTOMATA 200
Is Hilbert space discrete?
We show that discretization of spacetime naturally suggests discretization of
Hilbert space itself. Specifically, in a universe with a minimal length (for
example, due to quantum gravity), no experiment can exclude the possibility
that Hilbert space is discrete. We give some simple examples involving qubits
and the Schrodinger wavefunction, and discuss implications for quantum
information and quantum gravity.Comment: 4 pages, revtex, 1 figur
Models of Quantum Cellular Automata
In this paper we present a systematic view of Quantum Cellular Automata
(QCA), a mathematical formalism of quantum computation. First we give a general
mathematical framework with which to study QCA models. Then we present four
different QCA models, and compare them. One model we discuss is the traditional
QCA, similar to those introduced by Shumacher and Werner, Watrous, and Van Dam.
We discuss also Margolus QCA, also discussed by Schumacher and Werner. We
introduce two new models, Coloured QCA, and Continuous-Time QCA. We also
compare our models with the established models. We give proofs of computational
equivalence for several of these models. We show the strengths of each model,
and provide examples of how our models can be useful to come up with
algorithms, and implement them in real-world physical devices
FDTD/K-DWM simulation of 3D room acoustics on general purpose graphics hardware using compute unified device architecture (CUDA)
The growing demand for reliable prediction of sound fields in rooms have resulted in adaptation of various approaches for physical modeling, including the Finite Difference Time Domain (FDTD) and the Digital Waveguide Mesh (DWM). Whilst considered versatile and attractive methods, they suffer from dispersion errors that increase with frequency and vary with direction of propagation, thus imposing a high frequency calculation limit. Attempts have been made to reduce such errors by considering different mesh topologies, by spatial interpolation, or by simply oversampling the grid. As the latter approach is computationally expensive, its application to three-dimensional problems has often been avoided. In this paper, we propose an implementation of the FDTD on general purpose graphics hardware, allowing for high sampling rates whilst maintaining reasonable calculation times. Dispersion errors are consequently reduced and the high frequency limit is increased. A range of graphics processors are evaluated and compared with traditional CPUs in terms of accuracy, calculation time and memory requirements
Translation from Classical Two-Way Automata to Pebble Two-Way Automata
We study the relation between the standard two-way automata and more powerful
devices, namely, two-way finite automata with an additional "pebble" movable
along the input tape. Similarly as in the case of the classical two-way
machines, it is not known whether there exists a polynomial trade-off, in the
number of states, between the nondeterministic and deterministic pebble two-way
automata. However, we show that these two machine models are not independent:
if there exists a polynomial trade-off for the classical two-way automata, then
there must also exist a polynomial trade-off for the pebble two-way automata.
Thus, we have an upward collapse (or a downward separation) from the classical
two-way automata to more powerful pebble automata, still staying within the
class of regular languages. The same upward collapse holds for complementation
of nondeterministic two-way machines.
These results are obtained by showing that each pebble machine can be, by
using suitable inputs, simulated by a classical two-way automaton with a linear
number of states (and vice versa), despite the existing exponential blow-up
between the classical and pebble two-way machines
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