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Mathematics for Machine Learning
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Mathematics for Machine Learning
Farid Saberi-Movahed
Department of Applied Mathematics
Graduate University of Advanced Technology
January 23, 2021
Some important categories of
mathematics for machine learning
Farid Saberi-Movahed — Mathematics for Machine Learning
1
Contents
2
Eigenvalues and Eigenvectors
Similarity and Distance Learning
Graph-Based Methods
Matrix Decompositions
Matrix Norms
Some Potential and Hot Topics
Farid Saberi-Movahed — Mathematics for Machine Learning
Eigenvalues and Eigenvectors
3
Farid Saberi-Movahed — Mathematics for Machine Learning
Some applications
4
I
Dimensionality Reduction
I
Spectral Clustering
I
Graph-Based Methods
Farid Saberi-Movahed — Mathematics for Machine Learning
Dimensionality Reduction
5
Dimensionality reduction, or dimension reduction, is the
transformation of data
from a high-dimensional space into a low-dimensional space
so that
the low-dimensional representation retains
some meaningful properties of the original data.
Farid Saberi-Movahed — Mathematics for Machine Learning
Dimensionality Reduction
6
Farid Saberi-Movahed — Mathematics for Machine Learning
Dimensionality Reduction
7
I
Let us assume that the data matrix is defined as
X = [x (1) ; x (2) ; . . . ; x (m) ],
where each x (i) ∈ R1×n .
I
The aim of the dimensionality reduction is to find a low
dimensional representation
X̃ = [x̃ (1) ; x̃ (2) ; . . . ; x̃ (m) ].
I
This process is achieved by a mapping
ϕ : x (i) ∈ Rn −→ x̃ (i) ∈ Rk
x̃
Farid Saberi-Movahed — Mathematics for Machine Learning
(i)
(i)
= ϕ(x )
(k n)
Principal Component Analysis (PCA)
8
Farid Saberi-Movahed — Mathematics for Machine Learning
Spectral Clustering
9
Farid Saberi-Movahed — Mathematics for Machine Learning
Laplacian Matrix
10
I
In the graph theory, the Laplacian matrix (graph Laplacian) is a
matrix representation of a graph.
I
Given a simple graph G with m vertices, its Laplacian matrix
L ∈ Rm×m is defined as:
L = D − A,
where
I
I
A = [aij ] ∈ Rm×m is the adjacency (similarity) matrix of the graph.
D is the degree matrix and is defined as
D = diag(d11 , d22 , . . . , dmm ),
where
dii =
m
X
j=1
Farid Saberi-Movahed — Mathematics for Machine Learning
aij .
Spectral Clustering Algorithm
11
Farid Saberi-Movahed — Mathematics for Machine Learning
A Good Reference to Start with
Spectral Clustering
A Tutorial on Spectral Clustering
Ulrike von Luxburg
Farid Saberi-Movahed — Mathematics for Machine Learning
12
Similarity and Distance Learning
13
I
Clustering is one of the most fundamental unsupervised learning
techniques.
I
The goal of clustering is to divide a set of data points into
multiple clusters so that
1. points within a cluster have high similarity,
2. but are very dissimilar to points in other clusters.
Farid Saberi-Movahed — Mathematics for Machine Learning
Similarity and Distance Learning
14
Farid Saberi-Movahed — Mathematics for Machine Learning
Similarity
15
Farid Saberi-Movahed — Mathematics for Machine Learning
Distance Learning
16
I
Euclidean distance:
d(x, y ) = kx − y k2 .
I
Manhattan distance:
d(x, y ) = kx − y k1 .
I
Chebyshev distance:
d(x, y ) = kx − yk∞ .
I
Mahalanobis distance:
dM (x, y )2 = (x − y)T M(x − y ),
where M is a symmetric positive semidefinite matrix.
Farid Saberi-Movahed — Mathematics for Machine Learning
A Good Reference to Start with
Distance Learning
A Tutorial on Distance Metric Learning:
Mathematical Foundations, Algorithms and Software
Juan Luis Suarez
Salvador Garcia
Francisco Herrera
Farid Saberi-Movahed — Mathematics for Machine Learning
17
Graph-Based Methods
18
Farid Saberi-Movahed — Mathematics for Machine Learning
A General Framework of
a Graph-Based Method
I
I
I
Conducting a nearest-neighbor search.
Considering distance between points.
Using the eigen-information for embedding high-dimensional
points into a lower dimensional space.
Farid Saberi-Movahed — Mathematics for Machine Learning
19
Some Important Examples of
Graph-Based Methods
I
Laplacian Eigenmaps
I
Local Linear Embedding (LLE)
I
Isometric Mapping (ISOMAP)
I
Hessian Eigenmaps
I
Diffusion Maps
Farid Saberi-Movahed — Mathematics for Machine Learning
20
Two Good References to Start with
Manifold Learning
I
Review Paper: A. Izenman, Introduction to manifold learning,
Wiley Interdisciplinary Reviews: Computational Statistics,
4(5):439-46, 2012.
I
Book (Section 6.7): S. Theodoridis, Ko. Koutroumbas, Pattern
recognition, Academic Press, 2003.
Farid Saberi-Movahed — Mathematics for Machine Learning
21
Matrix Decompositions
22
I
Singular value decomposition (SVD): Given X ∈ Rn×d .
SVD:
X ≈ UΣV T .
I
Non-negative matrix factorization (NMF): Given X+ ∈ Rn×d .
Find non-negative matrix factors U ∈ Rn×k and H ∈ Rk×d such
that:
X+ ' U H,
s.t. U ≥ 0, and H ≥ 0.
I
Semi-NMF: X ≈ UH+ .
I
Convex-NMF: X ≈ XW+ H+ .
Farid Saberi-Movahed — Mathematics for Machine Learning
Non-Negative Matrix Factorization (NMF)
23
X ' U H,
s.t. U ≥ 0,
and
H ≥ 0.
In fact, each column vector of X can be presented as the linear
combination of the column vectors in U using coefficients supplied by
columns of H. That is,
xi ' U hi .
Farid Saberi-Movahed — Mathematics for Machine Learning
A Good Reference to Start with
Non-Negative Matrix Factorization
I
Review Paper: A.C. Turkmen, A review of nonnegative matrix
factorization methods for clustering, 2015.
Farid Saberi-Movahed — Mathematics for Machine Learning
24
Matrix Norms
25
For any arbitrary matrix A ∈ Rn×k , the Ll,p -norm is defined as follows:
kAkl,p


 p  p1
l
n
k
X
X



=
|ai,j |l   .
i=1
• k · k1 -norm: When l = p = 1,
j=1
kAk1 =
Pn Pk
i=1
j=1 |ai,j |.
P P
n
k
1
2
|ai,j |2 .
1
P Pk
2 2
• L2,1 -norm: When l = 2, p = 1, kAk2,1 = ni=1
.
j=1 |ai,j |
1 2
Pn
Pk
2 4
• L2,1/2 -norm: When l = 2, p = 1/2, kAk2,1/2 =
.
i=1
j=1 |ai,j |
• Frobenius norm: When l = p = 2,
Farid Saberi-Movahed — Mathematics for Machine Learning
kAkF =
i=1
j=1
Sparsity Learning
26
Farid Saberi-Movahed — Mathematics for Machine Learning
27
Some Potential and Hot Topics
Farid Saberi-Movahed — Mathematics for Machine Learning
Subspace Clustering
28
Subspace clustering is an extension of traditional clustering that
seeks to find clusters in different subspaces within a dataset.
I
A. Aldroubi, A. Sekmen, Reduced row echelon form and
non-linear approximation for subspace segmentation and
high-dimensional data clustering. Applied and Computational
Harmonic Analysis, 37(2), 271-287, 2014.
Farid Saberi-Movahed — Mathematics for Machine Learning
Self-Representation in Feature Selection
29
Let us assume that the feature representation of the data matrix is
X = [x1 , x2 , . . . , xn ],
where each xi ∈ Rm×1 .
The main idea behind the self-representation is that
each feature vector xi can be linearly represented by other features.

x1 ≈ z11 x1 + · · · + zi1 xi + · · · + zn1 xn




.

.


.
xi ≈ z1i x1 + · · · + zii xi + · · · + zni xn


.

..




xn ≈ z1n x1 + · · · + zin xi + · · · + znn xn
Farid Saberi-Movahed — Mathematics for Machine Learning
When Harmonic Analysis Meets
Machine Learning
When Harmonic Analysis Meets Machine Learning:
Lipschitz Analysis of Deep Convolution Networks
Radu Balan
Professor of Applied Mathematics
Applied Harmonic Analysis
University of Maryland
Farid Saberi-Movahed — Mathematics for Machine Learning
30
Graph Embedding
31
Graph embedding is an approach that is used to transform nodes,
edges, and their features into a lower dimension whilst maximally
preserving properties like graph structure and information.
Farid Saberi-Movahed — Mathematics for Machine Learning
A very Good Reference to Start with
Graph Neural Networks
Review Paper: Z. Wu, et al., A comprehensive survey on graph
neural networks, IEEE Transactions on Neural Networks and
Learning Systems, 2020.
Farid Saberi-Movahed — Mathematics for Machine Learning
32
33
Farid Saberi-Movahed — Mathematics for Machine Learning
34
Farid Saberi-Movahed — Mathematics for Machine Learning
Thank you for your attention!
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