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991.
One major idea in structured prediction is to assume that the predictor computes its output by finding the maximum of a score function. The training of such a predictor can then be cast as the problem of finding weights of the score function so that the output of the predictor on the inputs matches the corresponding structured labels on the training set. A similar problem is studied in inverse reinforcement learning (IRL) where one is given an environment and a set of trajectories and the problem is to find a reward function such that an agent acting optimally with respect to the reward function would follow trajectories that match those in the training set. In this paper we show how IRL algorithms can be applied to structured prediction, in particular to parser training. We present a number of recent incremental IRL algorithms in a unified framework and map them to parser training algorithms. This allows us to recover some existing parser training algorithms, as well as to obtain a new one. The resulting algorithms are compared in terms of their sensitivity to the choice of various parameters and generalization ability on the Penn Treebank WSJ corpus. 相似文献
992.
Using a call-by-value functional language as an example, this article illustrates the use of coinductive definitions and proofs in big-step operational semantics, enabling it to describe diverging evaluations in addition to terminating evaluations. We formalize the connections between the coinductive big-step semantics and the standard small-step semantics, proving that both semantics are equivalent. We then study the use of coinductive big-step semantics in proofs of type soundness and proofs of semantic preservation for compilers. A methodological originality of this paper is that all results have been proved using the Coq proof assistant. We explain the proof-theoretic presentation of coinductive definitions and proofs offered by Coq, and show that it facilitates the discovery and the presentation of the results. 相似文献
993.
José Ramón González de Mendívil José Enrique Armendáriz-Iñigo José Ramón Garitagoitia Francesc D. Muñoz-Escoí 《The Journal of supercomputing》2009,50(2):121-161
This paper provides a formal specification and proof of correctness of a basic Generalized Snapshot Isolation certification-based data replication protocol for database middleware architectures. It has been modeled using a state transition
system, as well as the main system components, allowing a perfect match with the usual deployment in a middleware system.
The proof encompasses both safety and liveness properties, as it is commonly done for a distributed algorithm. Furthermore,
a crash failure model has been assumed for the correctness proof, although recovery analysis is not the aim of this paper.
This allows an easy extension toward a crash-recovery model support in future works. The liveness proof focuses in the uniform
commit: if a site has committed a transaction, the rest of sites will either commit it or it would have crashed. 相似文献
994.
Nicolás Peña David Scarlatti Aníbal Ollero 《Journal of Intelligent and Robotic Systems》2009,54(1-3):39-59
The System Wide Information Management (SWIM) approach has been conceived to overcome the capacity and flexibility limitations of the current ATM systems. On the other hand the commercial applications of Unmanned Aerial Vehicles (UAVs) require the integration of these vehicles in the ATM. From this perspective, the unavoidable modernization of the ATM is seen as an opportunity to integrate the UAVs with the rest of the air traffic. This paper is devoted to study the feasibility and impact of the aggregation of UAVs on the future ATM supported by a SWIM inspired architecture. Departing from the existing technical documents that describe the fundamentals of SWIM we have explored the compatibility with a potential UAVs integration and also explored how the UAVs could help to improve the future ATM system. We will use the weather application as an example in both cases. 相似文献
995.
996.
Fumiya Iida Yohei Minekawa Jürgen Rummel André Seyfarth 《Robotics and Autonomous Systems》2009,57(2):139-144
Conventional models of bipedal walking generally assume rigid body structures, while elastic material properties seem to play an essential role in nature. On the basis of a novel theoretical model of bipedal walking, this paper investigates a model of biped robot which makes use of minimum control and elastic passive joints inspired from the structures of biological systems. The model is evaluated in simulation and a physical robotic platform by analyzing the kinematics and ground reaction force. The experimental results show that, with a proper leg design of passive dynamics and elasticity, an attractor state of human-like walking gait patterns can be achieved through extremely simple control without sensory feedback. The detailed analysis also explains how the dynamic human-like gait can contribute to adaptive biped walking. 相似文献
997.
Pattern classification with mixtures of weighted least-squares support vector machine experts 总被引:1,自引:1,他引:0
Clodoaldo A. M. Lima André L. V. Coelho Fernando J. Von Zuben 《Neural computing & applications》2009,18(7):843-860
Support Vector Machine (SVM) classifiers are high-performance classification models devised to comply with the structural risk minimization principle and to properly exploit the kernel artifice of nonlinearly mapping input data into high-dimensional feature spaces toward the automatic construction of better discriminating linear decision boundaries. Among several SVM variants, Least-Squares SVMs (LS-SVMs) have gained increased attention recently due mainly to their computationally attractive properties coming as the direct result of applying a modified formulation that makes use of a sum-squared-error cost function jointly with equality, instead of inequality, constraints. In this work, we present a flexible hybrid approach aimed at augmenting the proficiency of LS-SVM classifiers with regard to accuracy/generalization as well as to hyperparameter calibration issues. Such approach, named as Mixtures of Weighted Least-Squares Support Vector Machine Experts, centers around the fusion of the weighted variant of LS-SVMs with Mixtures of Experts models. After the formal characterization of the novel learning framework, simulation results obtained with respect to both binary and multiclass pattern classification problems are reported, ratifying the suitability of the novel hybrid approach in improving the performance issues considered. 相似文献
998.
The main aim of this paper is to predict NO and NO2 concentrations 4 days in advance by comparing two artificial intelligence learning methods, namely, multi-layer perceptron
and support vector machines, on two kinds of spatial embedding of the temporal time series. Hourly values of NO and NO2 concentrations, as well as meteorological variables were recorded in a cross-road monitoring station with heavy traffic in
Szeged, in order to build a model for predicting NO and NO2 concentrations several hours in advance. The prediction of NO and NO2 concentrations was performed partly on the basis of their past values, and partly on the basis of temperature, humidity and
wind speed data. Since NO can be predicted more accurately, its values were considered primarily when forecasting NO2. Time series prediction can be interpreted in a way that is suitable for artificial intelligence learning. Two effective
learning methods, namely, multi-layer perceptron and support vector regression are used to provide efficient non-linear models
for NO and NO2 time series predictions. Multi-layer perceptron is widely used to predict these time series, but support vector regression
has not yet been applied for predicting NO and NO2 concentrations. Three commonly used linear algorithms were considered as references: 1-day persistence, average of several
day persistence and linear regression. Based on the good results of the average of several day persistence, a prediction scheme
was introduced, which forms weighted averages instead of simple ones. The optimization of these weights was performed with
linear regression in linear case and with the learning methods mentioned in non-linear case. Concerning the NO predictions,
the non-linear learning methods give significantly better predictions than the reference linear methods. In the case of NO2, the improvement of the prediction is considerable, however, it is less notable than for NO. 相似文献
999.
Joaquín Nicolás Joaquín Lasheras Ambrosio Toval Francisco J. Ortiz Bárbara Álvarez 《Requirements Engineering》2009,14(1):27-46
Teleoperated systems for ship hull maintenance (TOS) are robotic systems for ship maintenance tasks, such as cleaning or painting
a ship’s hull. The product line paradigm has recently been applied to TOS, and a TOS reference architecture has thus been
designed. However, TOS requirements specifications have not been developed in any rigorous way with reuse in mind. We therefore
believe that an opportunity exists to increase the abstraction level at which stakeholders can reason about this product line.
This paper reports an experience in which this TOS domain was analyzed, including the lessons learned in the construction
and use of the TOS domain model. The experience is based on the application of extensions of well-known domain analysis techniques,
together with the use of quality attribute templates traced to a feature model to deal with non-functional issues. A qualitative
research method (action research) was used to carry out the experience. 相似文献
1000.
In an adaptive and intelligent educational system (AIES), the process of learning pedagogical policies according the students needs fits as a Reinforcement Learning (RL) problem. Previous works have demonstrated that a great amount of experience is needed in order for the system to learn to teach properly, so applying RL to the AIES from scratch is unfeasible. Other works have previously demonstrated in a theoretical way that seeding the AIES with an initial value function learned with simulated students reduce the experience required to learn an accurate pedagogical policy. In this paper we present empirical results demonstrating that a value function learned with simulated students can provide the AIES with a very accurate initial pedagogical policy. The evaluation is based on the interaction of more than 70 Computer Science undergraduate students, and demonstrates that an efficient and useful guide through the contents of the educational system is obtained. 相似文献