Binary field arithmetic is used in coding. The basic rules are very simple. Addition is as follows:
0+0=00+1=11+0=11+1=0
This also corresponds to the exclusive OR or XOR operator in digital logic. Subtraction results are identical to addition; there is no distinction between the two operations.
Multiplication is as follows:
0⋅0=00⋅1=01⋅0=01⋅1=1
Division is not defined or allowed.
Linearity means that if two input codewords are input to a system, X1 and X2, the output result is the same as if the sum of two codewords X1+X2 were input instead. A more mathematical way to express this idea is as follows: