51,564 research outputs found
On finding approximate solutions of qualitative constraint networks
Qualitative Spatial and Temporal Reasoning (QSTR) represents spatial and temporal information in terms of human comprehensible qualitative predicates and reasons about qualitative information by solving qualitative constraint networks (QCNs). Despite significant progress in the past three decades, more and more evidence has shown that it is inherently hard to find exact solutions for expressive qualitative constraints. In many applications, however, we are often required to make decisions in a very limited time. In these cases, finding a good approximate solution in seconds is much more desirable than waiting days for an exact solution. In this paper, we will exploit the algebraic structure of qualitative calculi (e.g. Interval Algebra and RCC8) as well as their conceptual neighbourhood graphs to develop approximate methods for consistency checking in QSTR. Moreover, we propose and empirically compare four independent methods to serve as tools for finding good approximate solutions for the given qualitative calculi. © 2013 IEEE
Incorporating the Basic Elements of a First-degree Fuzzy Logic and Certain Elments of Temporal Logic for Dynamic Management Applications
The approximate reasoning is perceived as a derivation of new formulas with the corresponding temporal attributes, within a fuzzy theory defined by the fuzzy set of special axioms. For dynamic management applications, the reasoning is evolutionary because of unexpected events which may change the state of the expert system. In this kind of situations it is necessary to elaborate certain mechanisms in order to maintain the coherence of the obtained conclusions, to figure out their degree of reliability and the time domain for which these are true. These last aspects stand as possible further directions of development at a basic logic level. The purpose of this paper is to characterise an extended fuzzy logic system with modal operators, attained by incorporating the basic elements of a first-degree fuzzy logic and certain elements of temporal logic.Dynamic Management Applications, Fuzzy Reasoning, Formalization, Time Restrictions, Modal Operators, Real-Time Expert Decision System (RTEDS)
t-Exponential Memory Networks for Question-Answering Machines
Recent advances in deep learning have brought to the fore models that can
make multiple computational steps in the service of completing a task; these
are capable of describ- ing long-term dependencies in sequential data. Novel
recurrent attention models over possibly large external memory modules
constitute the core mechanisms that enable these capabilities. Our work
addresses learning subtler and more complex underlying temporal dynamics in
language modeling tasks that deal with sparse sequential data. To this end, we
improve upon these recent advances, by adopting concepts from the field of
Bayesian statistics, namely variational inference. Our proposed approach
consists in treating the network parameters as latent variables with a prior
distribution imposed over them. Our statistical assumptions go beyond the
standard practice of postulating Gaussian priors. Indeed, to allow for handling
outliers, which are prevalent in long observed sequences of multivariate data,
multivariate t-exponential distributions are imposed. On this basis, we proceed
to infer corresponding posteriors; these can be used for inference and
prediction at test time, in a way that accounts for the uncertainty in the
available sparse training data. Specifically, to allow for our approach to best
exploit the merits of the t-exponential family, our method considers a new
t-divergence measure, which generalizes the concept of the Kullback-Leibler
divergence. We perform an extensive experimental evaluation of our approach,
using challenging language modeling benchmarks, and illustrate its superiority
over existing state-of-the-art techniques
Finding Temporally Consistent Occlusion Boundaries in Videos using Geometric Context
We present an algorithm for finding temporally consistent occlusion
boundaries in videos to support segmentation of dynamic scenes. We learn
occlusion boundaries in a pairwise Markov random field (MRF) framework. We
first estimate the probability of an spatio-temporal edge being an occlusion
boundary by using appearance, flow, and geometric features. Next, we enforce
occlusion boundary continuity in a MRF model by learning pairwise occlusion
probabilities using a random forest. Then, we temporally smooth boundaries to
remove temporal inconsistencies in occlusion boundary estimation. Our proposed
framework provides an efficient approach for finding temporally consistent
occlusion boundaries in video by utilizing causality, redundancy in videos, and
semantic layout of the scene. We have developed a dataset with fully annotated
ground-truth occlusion boundaries of over 30 videos ($5000 frames). This
dataset is used to evaluate temporal occlusion boundaries and provides a much
needed baseline for future studies. We perform experiments to demonstrate the
role of scene layout, and temporal information for occlusion reasoning in
dynamic scenes.Comment: Applications of Computer Vision (WACV), 2015 IEEE Winter Conference
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