De-Morgan was a great logician and mathematician. He had contributed much to logic. Among his contribution the following two theorems are important
It States that ―The complement of the sum of the variables is equal to the product of the complement of each variable‖. This theorem may be expressed by the following Boolean expression.
It states that the ―Complement of the product of variables is equal to the sum of complements of each individual variables‖. Boolean expression for this theorem is