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close this folderIntroduction Boolean Algebra - Lesson 2
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View the documentIntroduction
View the documentBoolean algebra
View the documentBoolean equations of logic circuits
View the documentNOR and NAN gates
View the documentDe Morgan's theorems

De Morgan's theorems

Augustus De Morgan was the first who found the link between logic and mathematics.


Fig. 2-8: Logic circuits with the same output

Although the circuits are different but the output, as we can see in the truth table, is equal. Therefore we can write:

De Morgan's First Theorem

Also if we compare the two circuits on the next page we can easily see that the output is the same, although the circuits are different.

(see Fig. 2-9)


Fig. 2-9: Logic circuits with the same output

So we can write:

De Morgan's Second Theorem

HO: How can you connect a NAND gate to get an inverter

Solution:


Figure

HO: How can you connect NAND gates to get an OR gate?

Solution:


Figure