46312706
Automatic handwriting gestures recognition using hidden Markov models
Hidden Markov models have been successfully employed in speech recognition and, more recently, in sign language interpretation. They seem adequate for visual recognition of gestures. In this paper, two problems often eluded are considered. We propose to use the Bayesian information criterion in order to determine the optimal number of model states. We describe the contribution of continuous models in opposition to symbolic ones. Experiments on handwriting gestures show recognition rate between 88% and 100%.
206630030
Statistical Gesture Recognition Through Modelling of Parameter Trajectories
The recognition of human gestures is a challenging problem that can contribute to a natural man-machine interface. In this paper, we present a new technique for gesture recognition. Gestures are modelled as temporal trajectories of parameters. Local sub-sequences of these trajectories are extracted and used to define an orthogonal space using principal component analysis. In this space the probabilistic density function of the training trajectories is represented by a multidimensional histogram, which builds the basis for the recognition. Experiments on three different recognition problems show the general utility of the approach.
19177138
Reconstruction Thresholds on Regular Trees
We consider the model of broadcasting on a tree, with binary state space, on the infinite rooted tree T k in which each node has k children. The root of the tree takes a random value 0 or 1, and then each node passes a value independently to each of its children according to a 2x2 transition matrix P . We say that reconstruction is possible if the values at the d th level of the tree contain non-vanishing information about the value at the root as d→∞ . Extending a method of Brightwell and Winkler, we obtain new conditions under which reconstruction is impossible, both in the general case and in the special case p 11 =0 . The latter case is closely related to the hard-core model from statistical physics; a corollary of our results is that, for the hard-core model on the (k+1) -regular tree with activity λ=1 , the unique simple invariant Gibbs measure is extremal in the set of Gibbs measures, for any k ≥ 2 .
53305414
Fast Byzantine Consensus
We present the first protocol that reaches asynchronous Byzantine consensus in two communication steps in the common case. We prove that our protocol is optimal in terms of both number of communication steps and number of processes for two-step consensus. The protocol can be used to build a replicated state machine that requires only three communication steps per request in the common case. Further, we show a parameterized version of the protocol that is safe despite f Byzantine failures and, in the common case, guarantees two-step execution despite some number t of failures (t les f). We show that this parameterized two-step consensus protocol is also optimal in terms of both number of communication steps and number of processes
28154888
Architecture of a Framework for Generic Assisting Conversational Agents
In this paper, we focus on the notion of Assisting Conversational Agents (ACA) that are embodied agents dedicated to the function of assistance for novice users of software components and/or web services. We discuss the main requirements of such agents and we emphasize the genericity issue arising in the dialogical part of such architectures. This prompts us to propose a mediator-based framework, using a dynamic symbolic representation of the runtime of the assisted components. Then we define three strategies for the development of the mediators that are validated by the implementation of experiences taken in various situations.
14531338
Building a Foundation System for Producing Short Answers to Factual Questions
In this paper we describe question answering research being pursued as a joint project between Columbia University and the University of Colorado at Boulder as part of ARDA’s AQUAINT program. As a foundation for targeting complex questions involving opinions, events, and paragraph-length answers, we recently built two systems for answering short factual questions. We submitted results from the two systems to TREC’s Q&A track, and the bulk of this paper describes the methods used in building each system and the results obtained. We conclude by discussing current work aiming at combining modules from the two systems in a unified, more accurate system and adding capabilities for producing complex answers in addition to short ones.
26598527
Large Tandem Queueing Networks with Blocking
Systems consisting of many queues in series have been considered by Glynn and Whitt (1991) and Baccelli, Borovkov and Mairesse (2000). We extend their results to apply to situations where the queues have finite capacity and so various types of “blocking” can occur. The models correspond to max-plus type recursions, of simple form but in infinitely many dimensions; they are related to “percolation” problems of finding paths of maximum weight through a 2-dimensional lattice with random weights at the vertices. Topics treated include: laws of large numbers for the speed of customers progressing through the system; stationary behaviour for systems with external arrival processes; a functional central limit theorem describing the behaviour of the “front of the wave” progressing through a system which starts empty; stochastic orderings for waiting times of customers at successive queues. Several open problems are noted.