4. (8 points)           

C*(A+B+!(!C+!D))*D 

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A*C*D + B*C*D + !(!C+!D)*C*D

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A*C*D + B*C*D + !!(C*D)*C*D

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A*C*D + B*C*D + C*D*CD

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A*C*D + B*C*D + C*D

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A*C*D + B*C*D + 1*C*D

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(A+B+1)*C*D

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1*C*D

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C*D

5. (4 points)            

!A+A*!B 

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(!A+A)*(!A+!B)

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(1)*(!A+!B)

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(!A+!B)

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!(A*B)