Tautology and Contradiction
Tautology and Contradiction: Overview
This topic covers concepts such as Tautology in Mathematical Reasoning, Fallacy/Contradiction in Mathematical Reasoning, Laws of Algebra of Statements, Idempotent Laws of Algebra of Statements, Associative Laws of Algebra of Statements, etc.
Important Questions on Tautology and Contradiction
Which of the following Boolean expression is a tautology?

Let and be any two propositions.
Statement I: is a tautology.
Statement II: is a fallacy.


The negation of is

For two statements and , prove the following relations of logical equivalence.

For two statements and , prove the following relations of logical equivalence.


If and are two logical statements, then which of the following is not commutative ?

Let two statements and is defined as below
,
Kota is in London.
Then truth values of these statements: are



The only statement among the following that is a tautology is

The logical equivalent statement of is


is equivalent to

The statement is equivalent to

Let Maths is interesting and Maths is easy, then is equivalent to

Let Maths is interesting and Maths is easy, then is equivalent to

Without using truth table, prove that is a tautology.

Using the rules of logic, prove the following logical equivalences.
