# Introduction

### Boolean Algebra

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This is an introduction to Boolean algebra tutorial.

Mathematician George Boole invented the Boolean Algebra. This algebra deals with the rules by which logical operations are carried out. So, a digital circuit in this system is represented as input and output symbols and the function of the circuit is expressed as a Boolean relationship between the symbols.

## Terms

• Binary Number System
• Binary Constant
• Binary Variable
• Basic Logical Operation
• Boolean Function

## Binary Number System

It is a number system consisting of only two digits 0 and 1. It is also called the base 2 number system. All the numbers in this system is expressed in 0s and 1s.

Example: Decimal number (8)10 is written as (1000)2 in binary.

## Binary Constant

A binary value that will not change is called a binary constant.

## Binary Variable

A binary variable is a symbolic name assigned to a binary value.

Example: A = 1010

Here, A is a variable having binary value 1010.

## Basic Logical Operation

Following are the basic logical operation.

• OR operation (+)
• AND operation (.)
• NOT operation (')

## The Logical OR operation (+)

Logical OR operation of two boolean variables A and B is written as X = A + B

It is also called logical addition.

The following table contains the input and output of the logical OR operation. So, if any one of the input is 1 then the output is 1, otherwise it is 0.

## The Logical AND operation (.)

Logical AND operation of two boolean variables A and B is written as X = A . B

It is also called logical multiplication.

The following table contains the input and output of the logical AND operation. So, if both the input is 1 then the output is 1, otherwise it is 0.

## The Logical NOT operation (')

Logical NOT operation performs inverse operation and converts 1 into 0 and 0 into 1.

The following table contains the input and output of the logical NOT operation. So, if the input is 1 then the output is 0 and if the input is 0 then the output is 1.

## Boolean Function

A boolean function is an algebraic expression formed using binary constants, binary variables and basic logical operators.

Example: Boolean Function
F = A + 1

where, A is a binary variable
+ is a Basic Logical Operator (OR)
and, 1 is a binary constant.

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