If result of any logical statement or expression is always TRUE or 1, it is called Tautology and if the result is always FALSE or 0 it is called Fallacy.
We will prove 1 + Y is a tautology with the help of truth table which is given below :
From truth table it is prove that 1 + Y is a tautology.
We will prove 0 . Y is a fallacy with the help of truth table which is given below :
From truth table it is prove that 0 . Y is a fallacy.