Competitive Network



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Competitive Network



Competitive Network

Student name

Mostafa Ahmed Ashour

faculty

Computers and Informatics

Level

3

Department

Computer Science

National id

29905161900518

Student code

1714103060

program

Computer Science

subject

Neural Network

1.introduction



A competitive network is typically a type of unsupervised machine learning, using the principle of competitive learning to provide results. Through specific mathematical and network modeling, competitive networks achieve various goals in input recognition and processing .it works by increasing the specialization of each node within the network. We set activation value 1and anther units 0.

2. research objectives

1.Designing competitive network.

2.Writing algorithm (pseudocode) of the competitive network.

3.using the competitive network to distinguish between the following two patterns

4.Finding a single layer network that has the same input/output characteristic




3.research

1- The Competitive network Design

The hamming network one of a competitive network.





First layer:



  1. Function Type: purelinear feed forward network

  2. Wight and bias represented as a matrix

  3. Wight of the first layer are the transpose of the prototype vectors

p1p2p Q

weight matrix :



And bias matrix:



output of the first layer is given by:




Second Layer:

a recurrent layer or (the competitive layer) with positive linear transfer function

The second layer is initialized with the output of the first layer.


A 2(0) = a 1
a2 (t + 1) poslin W 2a 2 = ( (t))
The neuron with the largest initial condition will win the competiton

ai2t + 1poslin ( ai2taj2 t )

i j

Algorithm and Pseudocode


Initialize weights

Find the winning weight vector which is closest to presented Input vector

Modify the winner so as to move closer to the input vector

Modify weights so as to make them more similar to the values in the input vector.


Pseudocode:
Initialize weights

{wi}, i = 1, 2, ..., k

select a pattern X

Find the winner neuron:

b = argmink| x – wi |

Update the winner neuron

∆wb = γ(x − wb)

Goto step 2 until no significant change in weights.

3- using the competitive network to distinguish between the following two patterns

p1=[1 -1 1 -1] , p2 = [1 1 -1 -1]


W1= , b =
a11 = purelin (w1p1+b1)  a11= purelin ( + )

a11 = purelin ( )

a12 = purelin (w1p2+b1)  a12 = purelin ( + )

a12 = purelin ( )


w2 =
a2 = poslin (w2 a1)  a21 = poslin ( )

a21 = poslin ( )


a22 = poslin ( )
a22 = poslin ( )




W1= , b1 = , w2 = , b2 =


a1 = purelin (n) = (w1*p)+b1 , a2 = purelin (n2) = (w2*a1 )+b2
a2= w2*(w1*p+b1)+b2  a2 = (w2*w1)*p +(w2*b1 +b2)

w new = w2*w1 , b new = w2*b1 +b2


w new = = [-1 2] , b new = + = - 0.5

Example :

p =

a1 = purelin (n) = (w1*p)+b1  a1 = purelin ( + )

a1 = purelin ( ) =
a2 = purelin (n2)= n2 = (w2*a1 )+b2  a2 = purelin ( + )

a2 = purelin ([-3.5]) = [-3.5]


the Network :
a new = purelin ( w new p +b new )  a new = purelin ( [-1 2] + [- 0.5] )

a new = purelin ( [-3.5] ) = [ -3.5]





4.conclusion

At long last ,competitive neurons are initialized with the outputs of the previous (feedforward) layer wich indicate the correlation between the input vector and prototype vector .

Then the neurons compete with each other to determine a winner .

After competition onley one neuron will have a non zero output

The winning neuron indicates which category of input was presented to the network



5.References

  1. neural network online course

  2. neural network design(book)

  3. https://jsalatas.ictpro.gr/implementation-of-competitive-learning-networks-for-weka/

  4. https://onlinelibrary.wiley.com/doi/pdf/10.1207/s15516709cog0901_5



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