53,367 research outputs found
Optimization and Abstraction: A Synergistic Approach for Analyzing Neural Network Robustness
In recent years, the notion of local robustness (or robustness for short) has
emerged as a desirable property of deep neural networks. Intuitively,
robustness means that small perturbations to an input do not cause the network
to perform misclassifications. In this paper, we present a novel algorithm for
verifying robustness properties of neural networks. Our method synergistically
combines gradient-based optimization methods for counterexample search with
abstraction-based proof search to obtain a sound and ({\delta}-)complete
decision procedure. Our method also employs a data-driven approach to learn a
verification policy that guides abstract interpretation during proof search. We
have implemented the proposed approach in a tool called Charon and
experimentally evaluated it on hundreds of benchmarks. Our experiments show
that the proposed approach significantly outperforms three state-of-the-art
tools, namely AI^2 , Reluplex, and Reluval
Informed MCMC with Bayesian Neural Networks for Facial Image Analysis
Computer vision tasks are difficult because of the large variability in the
data that is induced by changes in light, background, partial occlusion as well
as the varying pose, texture, and shape of objects. Generative approaches to
computer vision allow us to overcome this difficulty by explicitly modeling the
physical image formation process. Using generative object models, the analysis
of an observed image is performed via Bayesian inference of the posterior
distribution. This conceptually simple approach tends to fail in practice
because of several difficulties stemming from sampling the posterior
distribution: high-dimensionality and multi-modality of the posterior
distribution as well as expensive simulation of the rendering process. The main
difficulty of sampling approaches in a computer vision context is choosing the
proposal distribution accurately so that maxima of the posterior are explored
early and the algorithm quickly converges to a valid image interpretation. In
this work, we propose to use a Bayesian Neural Network for estimating an image
dependent proposal distribution. Compared to a standard Gaussian random walk
proposal, this accelerates the sampler in finding regions of the posterior with
high value. In this way, we can significantly reduce the number of samples
needed to perform facial image analysis.Comment: Accepted to the Bayesian Deep Learning Workshop at NeurIPS 201
Crowd Counting with Decomposed Uncertainty
Research in neural networks in the field of computer vision has achieved
remarkable accuracy for point estimation. However, the uncertainty in the
estimation is rarely addressed. Uncertainty quantification accompanied by point
estimation can lead to a more informed decision, and even improve the
prediction quality. In this work, we focus on uncertainty estimation in the
domain of crowd counting. With increasing occurrences of heavily crowded events
such as political rallies, protests, concerts, etc., automated crowd analysis
is becoming an increasingly crucial task. The stakes can be very high in many
of these real-world applications. We propose a scalable neural network
framework with quantification of decomposed uncertainty using a bootstrap
ensemble. We demonstrate that the proposed uncertainty quantification method
provides additional insight to the crowd counting problem and is simple to
implement. We also show that our proposed method exhibits the state of the art
performances in many benchmark crowd counting datasets.Comment: Accepted in AAAI 2020 (Main Technical Track
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