Q8.
Calculate the output of neuron $Y$ for the net shown in figure. Use binary and bipolar sigmoidal activation functions.
![enter image description here][2]
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Solution: The net input:
$y_{in}=b+x_1w_1+x_2w_2$
$y_{in}=0.9+0.2\times 0.7+0.3\times 0.8$
$y_{in}=0.9+0.14+0.24$
$y_{in}=1.28$
(i) Binary Sigmoidal Activation Function
$y=f(y_{in})=\dfrac 1{1+e^{-y_{in}}}=\dfrac 1{1+e^{-1.28}}$
(ii) Bipolar Sigmoidal Activation Function,
$y=f(y_{in})=\dfrac 2{1+e^{-y_{in}}}-1=\dfrac {1-e^{-1.28}}{1+e^{-1.28}}$
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\ltDIV class='paper-question'\gt
\ltDIV class='paper-ques-desc'\gt
\ltb\gtQ9.\lt/b\gt
Design neutral using M-P neuron to implement using binary input
(i) NOT logic
(ii) OR
(iii) NAND
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Solution: (i) OR
![enter image description here][3]
$y_{in}=x_1w_1+x_2w_2$
Case 1: Assume $w_1=w_2=1$
$(1,1) - y_{in}=2$
$(1,0) - y_{in}=1$
$(0,1) - y_{in}=1$
$(0,0) - y_{in}=0$
Setting threshold as 2 will not work.
Case 2: Assume $w_1=1, w_2=-1$
$(1,1) - y_{in}=0$
$(1,0) - y_{in}=1$
$(0,1) - y_{in}=-1$
$(0,0) - y_{in}=0$
Setting threshold as 1 will not work.
Case 3: Assume $w_1=-1, w_2=1$
$(1,1) - y_{in}=0$
$(1,0) - y_{in}=-1$
$(0,1) - y_{in}=1$
$(0,0) - y_{in}=0$
Setting threshold as 1 will not work.
Case 4: Assume $w_1=-1, w_2=-1$
$(1,1) - y_{in}=-2$
$(1,0) - y_{in}=-1$
$(0,1) - y_{in}=-1$
$(0,0) - y_{in}=0$
$\theta\ge nw-p\\theta\ge2\times(0)-1\\theta\ge-1$