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kumar-shridhar committed Jan 8, 2019
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2 changes: 1 addition & 1 deletion Abstract/abstract.tex
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\newline


In the first part of the thesis, the Bayesian Neural Network is explained and it is applied to an Image Classification task. The results are compared to point-estimates based architectures on MNIST, CIFAR-10, CIFAR-100 and STL-10 datasets. Moreover, uncertainties are calculated and the architecture is pruned and a comparison between the results is drawn.
In the first part of the thesis, the Bayesian Neural Network is explained and it is applied to an Image Classification task. The results are compared to point-estimates based architectures on MNIST, CIFAR-10, and CIFAR-100 datasets. Moreover, uncertainties are calculated and the architecture is pruned and a comparison between the results is drawn.

In the second part of the thesis, the concept is further applied to other computer vision tasks namely, Image Super-Resolution and Generative Adversarial Networks. The concept of BayesCNN is tested and compared against other concepts in a similar domain.

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7 changes: 6 additions & 1 deletion Chapter2/chapter2.tex
Expand Up @@ -215,6 +215,11 @@ \section{Model Weights Pruning}
efficient inference using these sparse models requires purpose-built hardware capable of loading sparse matrices and/or performing sparse matrix-vector operations. Thus the overall memory usage is reduced with the new pruned model.


There are several ways of achieving the pruned model, the most popular one is to map the low contributing weights to zero and reducing the number of overall non-zero valued weights. This can be achieved by training a large sparse model and pruning it further which makes it comparable to training a small dense model. Pruning away the less salient features to zero has been used in this thesis and is explained in details in Chapter 4.
There are several ways of achieving the pruned model, the most popular one is to map the low contributing weights to zero and reducing the number of overall non-zero valued weights. This can be achieved by training a large sparse model and pruning it further which makes it comparable to training a small dense model.

Assigning weights zero to most features and non-zero weights to only important features can be formalized by applying the $L_0$ norm, where $L_0 = ||\theta||_0 = \sum{_j} \delta (\theta_j \neq 0)$, and it applies a constant penalty to all non-zero weights.
$L_0$ norm can be thought of a feature selector norm that only assigns non-zero values to feature that are important. However, the $L_0$ norm is non-convex and hence, non-differentiable that makes it a NP-hard problem and can be only efficiently solved when $P = NP$.
The alternative that we use in our work is the $L_1$ norm, which is equal to the sum of the absolute weight values, $||\theta||_1 = \sum_j |\theta_j|$. $L_1$ norm is convex and hence differentiable and can be used as an approximation to $L_0$ norm \cite{tibshirani1996regression}. $L_1$ norm works as a sparsity inducing regularizer by making large number of coefficients equal to zero, working as a great feature selector in our case. Only thing to keep in mind is that the $L_1$ norm do not have a gradient at $\theta_j = 0$ and we need to keep that in mind.
Pruning away the less salient features to zero has been used in this thesis and is explained in details in Chapter 4.


4 changes: 2 additions & 2 deletions Chapter6/chapter6.tex
Expand Up @@ -83,9 +83,9 @@ \subsection{Empirical Analysis}

\begin{figure}[H]
\begin{center}
\includegraphics{Chapter6/Figs/camel_LR.png}
\includegraphics[height=.38\textheight]{Chapter6/Figs/camel_SR.png}
\label{fig:CamelSR}
\caption{Generated Super Resolution Image}
\caption{Generated Super Resolution Image scaled to 40 percent to fit}
\end{center}
\end{figure}

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8 changes: 8 additions & 0 deletions References/references.bib
Expand Up @@ -603,4 +603,12 @@ @article{hafner2018reliable
journal={arXiv preprint arXiv:1807.09289},
year={2018}
}
@article{tibshirani1996regression,
title={Regression shrinkage and selection via the lasso},
author={Tibshirani, Robert},
journal={Journal of the Royal Statistical Society. Series B (Methodological)},
pages={267--288},
year={1996},
publisher={JSTOR}
}

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