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nsanthan committed May 3, 2023
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40 changes: 40 additions & 0 deletions morea/neural-networks/#experience-auto.md#
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---
title: "Autoencoders"
published: true
morea_id: experience-auto
morea_type: experience
morea_summary: "Autoencoders and SVD"
morea_start_date: "2021-07-15T23:00"
morea_labels:
---

First review the section about eigenvalues and eigenspaces
[here]. Recall that \({\mathbb R}^p\) represents the linear space of
all vectors with \(p\) real coordinates. For a matrix \(n\times p\)
matrix \(X\), one can use spectral decomposition of \(X^TX\)
(respectively \(XX^T\)) to find an orthonormal basis for \({\mathbb
R}^p\) (respectively \({\mathbb R}^n\)) using eigenvectors of \(X^TX\)
(respectively \(XX^T\)), and therefore for the rows (respectively
columns) of \(X\). Assume that \(n \ge p\), and let the eigenvalues
of \(X^TX\) be \(\lambda_1\ge \lambda_2 \cdots \ge \lambda_p\), then
the highest \(p\) eigenvalues of \(XX^T\) are also
\(\lambda_1, \lambda_2 \upto \lambda_p\), while the remaining \(n-p\)
eigenvalues are all 0.


Let \(V\) (respectively \(U\)) be the matrix formed
by placing as columns the orthonormal basis obtained by the
eigendecomposition of \(X^TX\) (respectively \(XX^T\)).
Let \(\Sigma\)
be the \(n\times p\) matrix formed with the positive square roots of
the eigenvalues of \(X^TX\) in all the diagonal locations.
The singular value decomposition observes that
$$ X = U \Sigma V^T. $$

The following
[notebook](https://uhm-descartes.github.io/ee445/morea/neural-networks/autoencoder.ipynb)
shows you how to build a neural network that recovers the singular
value decomposition, the autoencoder. In the assessment, you will
reuse the code, but with non-linear activations to project the MNIST
dataset into a low dimensional manifold.

1 change: 1 addition & 0 deletions morea/neural-networks/.#experience-auto.md
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[email protected]:1683013381
26 changes: 20 additions & 6 deletions morea/neural-networks/assessment-nn.md
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---
title: "CHANGE ME"
published: false
morea_id: assessment-CHANGE-ME
morea_summary: "CHANGE ME"
title: "Assessment"
published: true
morea_id: assessment-nn
morea_summary: "Neural Networks"
morea_outcomes_assessed:
# - outcome-CHANGE-ME
morea_type: assessment
morea_start_date: "2021-07-16T09:00"
morea_labels:
---
# CHANGE ME
# Problems

TBD
* Use a feedforward architecture to train and predict on the CIFAR-10
and Fashion-MNIST dataset. Here, you may need to use dropout to
train better and reduce overfitting---find out how to implement this
technique. We discussed dropout very briefly in class, so you may want
to look up Dropout techniques online for more background.

* Project the MNIST dataset into as small a manifold as
possible. Meaning, you should come up with two transformations (we
will call them encoder and decoder). The encoder should represent
each \(28\times 28\) test image into a small vector (you can have
this vector have less than 10 coordinates, but it is ok if your
output is slightly larger too), but that doesn't lose
information---namely the decoder can reconstruct the original image
(with negligible loss) from the small vector output from the
encoder.
14 changes: 14 additions & 0 deletions morea/neural-networks/assessment-nn.md~
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---
title: "CHANGE ME"
published: false
morea_id: assessment-CHANGE-ME
morea_summary: "CHANGE ME"
morea_outcomes_assessed:
# - outcome-CHANGE-ME
morea_type: assessment
morea_start_date: "2021-07-16T09:00"
morea_labels:
---
# CHANGE ME

TBD
2 changes: 1 addition & 1 deletion morea/neural-networks/module-nn.md
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morea_start_date: "2021-07-12"
morea_end_date: "2021-07-16"
morea_labels:
morea_sort_order: 21
morea_sort_order: 81
---

CHANGE ME

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