# Computer Science Principles V11

Clive W. Humphris

BOOLEAN ALGEBRA: Boolean Postulates in logic 0 and 1. A postulate is a logic assumption. Boolean logic is derived from ten such assumptions for AND, OR and NOT functions. The NOT gate output is inverted and represented by an over-bar symbol. Each function when driven by given logic 0 or 1 to its input(s) will result in a defined output. This can be confirmed by referring to the logic gate topics.

Boolean algebra is therefore a short-hand way of writing and simplifying combinations of logic symbols.

The postulates are shown as pairs, where inverting the input(s) and changing the symbol (exception being the NOT gate) results in the opposite logic output.

To become familiar with these postulates derive each equivalent gate and its logic inputs and compare with those shown by selecting the gate symbols. As we develop this topic further it will not be necessary to draw the gates to arrive at a simplification, just remember the equivalent operators [.], [+] and over-bar logic representations.