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Intelligent System (CSE-523)

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Intelligent Computing

  • A new Computing Paradigm that is reshaping the traditional computing.
  • Computing paradigms are fundamental approaches to how we design, build, and use computer systems to solve problems and achieve specific goals.
  • They represent different ways of organizing computation, data, and computer systems.

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Computing Paradigm

  • Core Paradigms: (Computing before Cloud and Modern Computing)
    • Sequential/Imperative
    • Functional
    • Object-Oriented

  • Distributed Computing and Parallel Computing
    • Networked Computers solve a particular problem.
    • Multiple processors within a single machine.

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Modern Computing Paradigm

  • Cloud Computing: Computing resources as a service over the internet.
  • Edge Computing: Processes data closer to the source (e.g., IoT devices, sensors) to reduce latency and bandwidth usage, often complementing cloud computing.
  • Quantum Computing: Uses quantum mechanics to perform computations.
  • Cognitive Computing: Aims to create systems that mimic human thought processes, including learning, problem-solving, and decision-making.

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Intelligent Computing

Definition(Zhu et al, 2022): Intelligent computing is the area that encompasses the new computing theoretical methods, architecture systems, and technical capabilities in the era of digital civilization that supports the interconnection of all the world. Intelligent computing targets computational tasks with the minimum cost according to the specific actual needs, matching adequate computational power, invoking the finest algorithm, and obtaining optimal results.

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Intelligent Computing

  • Intelligent computing is a field that encompasses emerging computational theories, system architectures, and technical capabilities tailored for the digital age.

  • Its goal is to provide efficient, secure, autonomous, reliable, and transparent computing services to support large-scale and complex computational tasks.
  • In Intelligent Computing, human society, the physical world, and information space are integrated.

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Intelligent Computing

Figure 1: An overview of intelligent computing based on the fusion of human social space, physical

space, and information space.

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Evaluation Criteria

  • Sessional Assessment: 10%
  • Mid Semester Exam: 30%.
  • End Semester Exam: 50%.
  • Quiz: 10%

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Evaluation Criteria(Sessional Assessment: 10%)

  • Each student is required to spend approximately 12 hours over the semester—typically around one hour per week—at the Coforge Data & AI Lab: 10%. [10.00-16.00]

  • Each student needs to register his(her) biometric @ Coforge Data & AI Lab.

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Mode of Learning

  • Online Mode:
    • Everyone will get access to the online learning platform Percipio (ai-datalab.percipio.com)
        • AI for Programmers:

  • Offline Classes.

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Major Topics to be covered in this class

  • Artificial Neural Networks
  • Deep Neural Network (Mixed Mode)
  • Recommender System.
  • Anomaly Detection System
  • Spiking Neural Networks.

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Online Learning (AI for Programmers)

  • AI & ML Foundations: Classification, Clustering, Evaluation

  • Deep Learning: CNNs, RNNs, GANs, Attention Models

  • Generative AI: ChatGPT, Prompting, Transformer models

  • Prompt Engineering: Introduction, categories, task-based prompting

  • Responsible AI: Ethics, Risks, Mitigation strategies

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Artificial Neural Networks

  • The term neural network derives its origin from human brain that consists of a massively parallel architecture of large number of neurons.
  • Biological neural network can perform various tasks: perceptual, recognition, etc., much faster than even today’s high-performance computing systems.
  • Biological neural network inspired researchers to think if there is any way to make the computer mimic the networking and the complex interconnections that exist between the nerve cells in the human brain.

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Biological Neuron

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History: Artificial Neural Networks

  • McCulloch and Pits (1943): Introduced the idea of Neural Networks as Computing Machines.

  • Hebb (1949): Postulated the first rule for self-organized learning

  • Rosenblatt (1958): Proposed the perceptron as the first model for learning with a teacher

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McCulloch-Pitt’s Model

  • Proposed by Warren McCulloch and Walter Pitts in 1943.

  • This model imitates the functionality of a biological neuron, thus is also called Artificial Neuron.

  • An artificial neuron accepts binary inputs (i.e., 0 or 1) and produces a binary output based on a certain threshold value which can be adjusted. This can be mainly used for classification problems.

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McCulloch-Pitt’s Model

Different parts of McCulloch-Pitts Neuron Model

  1. Neuron: It is a computational unit which accepts incoming input signals. The input signals are computed and an output is fired. The neuron further consists of following two elements:
    • Summation function: Computes summation of the inputs.
    • Activation function: This is basically a threshold function which checks if the summation is greater than or equal to a preset value. If yes, the neuron should fire (i.e., produce output 1), and if no, the neuron should not fire (i.e., produce output 0).

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McCulloch-Pitt’s Model

Different parts of McCulloch-Pitts Neuron Model

2. Weighted Inputs and Summation: Each input has an associated weight. Positive weights represent excitatory inputs, encouraging the neuron to fire, while negative weights signify inhibitory inputs, potentially preventing the neuron from firing.

3. Output: This is simply the output of the neuron which again can take only binary values of 0 or 1. The value of 0 indicates that the neuron does not fire, the value of 1 indicates the neuron does fire.

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McCulloch-Pitt’s Model

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McCulloch-Pitt’s Model

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Realizing Simple Functions with McCulloch-Pitt’s Model

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McCulloch-Pitt’s Model

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Disadvantages of MCP Neuron

  • Binary Output Limitation
  • Fixed Weights
  • Lack of Learning
  • Inability to Handle Non-Linearities
  • Limited Complexity.
  • Scalability.

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Donald Hebb's Hebbian Learning (1949)

"Neurons that fire together, wire together".

  • In 1949, Donald Hebb proposed one of the key ideas in biological learning, commonly known as Hebb’s Law.
  • Hebb’s Law states that if neuron i is near enough to excite neuron j and repeatedly participates in its activation, the synaptic connection between these two neurons is strengthened and neuron j becomes more sensitive to stimuli from neuron i.

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Donald Hebb's Hebbian Learning (1949)

  1. The Hebbian rule states that if two interconnected neurons are simultaneously and persistently active, the strength of the synaptic connection (weight) between them should increase.

⇒ If two neurons on either side of a connection are activated synchronously, then the weight of that connection is increased.

  1. If two neurons on either side of a connection are activated asynchronously, then the weight of that connection is decreased.

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Donald Hebb's Hebbian Learning (1949)

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Donald Hebb's Hebbian Learning (1949)

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Apply Hebbian Rule

x1

x2

y (Output)

-1

-1

-1

-1

1

-1

1

-1

-1

1

1

1

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  1. Initialize all weight wi=0; including Bias=0; W0 =[0 0 0];
  2. Set activations for input units with the input vector Xi for i = 1 to n.
  3. Set the corresponding output value to the output neuron, i.e. yi.
  4. Update weight and bias by applying Hebb rule for all i = 1 to n:

wnew=wold+ l.xi.y , l=learning rate (Assume 1.0 here)

b=bold + y

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First Iteration:

w(new) = w(old) + x(1)y(1) = [ 0 0 0 ]T + [ -1 -1 1 ]T . [ -1 ] = [ 1 1 -1 ]T

2nd Iteration:

w(new) = [ 1 1 -1 ]T + [ -1 1 1 ]T . [ -1 ] = [ 2 0 -2 ]T

3rd Iteration:

w(new) = [ 2 0 -2]T + [ 1 -1 1 ]T . [ -1 ] = [ 1 1 -3 ]T

4th Iteration:

w(new) = [ 1 1 -3]T + [ 1 1 1 ]T . [ 1 ] = [ 2 2 -2 ]T

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Decision Boundary:

x1w1+x2w2+B=y

2x1+2x2-2=0

x1+x2=1

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Table

x1

x2

Y

-1

-1

-1

-1

1

1

1

-1

1

1

1

-1

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Single Layer Perceptron (1958)

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  • Perceptron is the simplest form of neural network used for classification of linearly separable patterns.
  • It consists of a single neuron with adjustable weights and bias.
  • The algorithm used to adjust the free parameters first appeared in a learning procedure developed by Rosenblatt (1958) for his perceptron brain model
  • He proved that if objects are drawn from two linearly separable classes, then the perceptron algorithm converges and positions the decision surface in the form of a hyper-plane between the two classes.

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  • The perceptron built around a single neuron is limited to performing classification with only two classes.
  • Expanding the output layer by including more neurons will help is performing multi-class classification, but the classes must be linearly separable for the perceptron to work properly.
  • As long as we look upon perceptron as an object classifier, we need to consider the case of a single output neuron only. Extension of the theory to the case of more than one neuron is trivial.
  • A single neuron forms the basis of an Adaptive Filter.

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Adaptive Linear Filtering (Widrow and Hoff, 1960)

  • Consider a dynamical linear system with unknown mathematical characterization.
  • Only a set of input-output patterns is available which is generated by the system at regular time instants
  • Assume the input stimulus is m-dimensional
  • The system will then have m input nodes. Without loss of generality let us assume there is a single output node
  • A m-dimensional stimulus x(i) is applied across the m input nodes of the system.

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Adaptive Linear Filtering (Widrow and Hoff, 1960)

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Adaptive Linear Filtering (Widrow and Hoff, 1960)

  • The external behavior of the system is described by the data set

D = {x(i),d(i);i=1,2,3,…,n,..} where x(i) = [x1(i) x2(i) …xm(i)]T.

  • The samples comprising D are identically distributed according to some unknown probability law.
  • m is the dimensionality of the input space or simply dimensionality.

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Adaptive Linear Filtering (Widrow and Hoff, 1960)

  • The stimulus x(i) can arise in one of the fundamentally different ways: spatial and temporal
    • The m elements of x(i) originate at different points in space, and x(i) is called a snapshot of the data
    • The m elements of x(i) represent the set of present and the previous (m-1) values of some excitation that are uniformly spaced in time
    • Our problem is to design a multi-input single-output model of the unknown dynamic system
    • The model operates under the influence of an algorithm that initializes a number of free parameters of the network and updates them iteratively to reach the optimum solution

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Adaptive Linear Filtering (Widrow and Hoff, 1960)

  • Free parameters are those parameters in the model that can be adjusted in each iteration to reach the optimum solution
  • The algorithm to train a linear adaptive filter starts with arbitrary setting of the weight parameter
  • Adjustments to these free parameters in response to statistical variations in the system’s behavior is made on a continuous basis.
  • Computations of adjustments to the synaptic weights must be made inside a time interval that is one sampling period long

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Adaptive Linear Filtering (Widrow and Hoff, 1960)

  • ADALINE was developed in 1960 at Stanford. It's one of the earliest trainable neural network models, and it introduced the LMS (Least Mean Squares) learning algorithm. It is one of the most widely used adaptive filtering algorithms even today.
  • The learning rule: LMS / Widrow-Hoff Delta Rule

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The learning rule: LMS / Widrow-Hoff Delta Rule (Widrow and Hoff, 1960)

  • Goal is to minimize mean squared error (MSE) between the actual output and predicted output computed as linear sum .
  • Error signal:

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Unconstrained Optimization Techniques

  • Consider a cost function C(w) that is continuously differentiable function of some unknown parameter w.
  • The function C(w) maps elements of w into real numbers
  • How to choose the parameter vector w of an adaptive filtering problem so that it behaves in an optimum manner?
  • We need to find an optimum solution w* that satisfies the condition C(w*)<C(w) for all w.
  • The unconstrained optimization problem can be stated as follows: Minimize the cost function C(w) w.r.t w.

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Unconstrained Optimization Techniques

  •  

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Unconstrained Optimization Techniques

We will learn three techniques:

Method of Steepest Descent

Gauss Newton’s Method

Newton’s Method

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Steepest Descent (Gradient Descent Method)

  •  

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Steepest Descent

  •  

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f(x,y)=x2+2y2

  1. Compute Gradient:

  1. Initialize :

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Example: Steepest Descent

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Rosenblatt: The perceptron - a probabilistic model for information storage and organization in the brain. Psychological Review, 1958.

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Perceptron (1958)

Basic Idea: The perceptron tries to learn a weight vector w such that

yi*(wTxi)>0 for all i.

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Perceptron Criterion

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Gradient effect on Perceptron Criterion

Taking derivative:

Update: w(n+1)=w(n)- η*J(w)

=w(n)+ η Σyixi.

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Basic Architecture of Perceptron

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Basic Architecture of Perceptron

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Perceptron Learning Rule

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Perceptron Learning Rule

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Example of Perceptron Learning Rule

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Example of Perceptron Learning Rule

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Minsky and Papert: Perceptrons: An introduction to computational geometry. MIT Press, 1969.

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1979: Fukushima’s Neocognitron

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1979: Fukushima’s Neocognitron

  • Aimed to solve the problem of shift-invariant pattern recognition – the ability to recognize an object regardless of its position in the visual field.
  • The structure of this network has been suggested by that of the visual nervous system of the vertebrate.
  • The network is self-organized by "learning without a teacher", and acquires an ability to recognize stimulus patterns based on the geometrical similarity (Gestalt) of their shapes without affected by their position nor by small distortion of their shapes.

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1979: Fukushima’s Neocognitron

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Learning Mechanism: Fukushima’s Neocognitron

  • Uses unsupervised learning for S-cells (self-organization).�
  • Based on a Hebbian-like rule (cells that fire together, wire together).

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1986: Back Propagation

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1986: Back Propagation

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1986: Back Propagation

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1986: Back Propagation

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1986: Back Propagation

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1986: Back Propagation

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1986: Back Propagation

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1986: Back Propagation

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Logistic Regression and Computation Graph