Analyzing the Setup
When you look at a statement like (∼(P∧Q))∨((∼P)∧Q)⇒((∼P)∧(∼Q)), it is easy to feel overwhelmed by the symbols. Logic is not about memorizing tables; it is about visualizing the structure of reality.
Let us break this down into a journey of discovery.
Deconstructing the Antecedent
First, let us look at the Antecedent, which we will call
L. It is defined as:
L=(∼(P∧Q))∨((∼P)∧Q)
Instead of panicking, let's use the power of Venn diagrams. Imagine two circles, P and Q, inside a universal set with four distinct regions:
Region 1: P only
Region 2: P and Q (Intersection)
Region 3: Q only
Region 4: Outside both
The first part, ∼(P∧Q), is a classic application of De Morgan's Law. It represents everything except the intersection of P and Q, covering Regions 1, 3, and 4.
The second part, (∼P)∧Q, represents the region inside Q but outside P, which is exactly Region 3. When we take the union of these two, we combine Regions 1, 3, 4 with Region 3.
Since Region 3 is already included, the union remains Regions 1, 3, and 4. Thus, our antecedent L simplifies to ∼(P∧Q).
The Consequent and the Implication Bridge
Now, let's look at the Consequent, R=(∼P)∧(∼Q). This represents the region outside both circles, which is Region 4.
We now face the implication:
L⇒R. Never try to evaluate an implication directly; always use the identity:
L⇒R≡(∼L)∨R
We know L covers Regions 1, 3, and 4. Therefore, ∼L must be the only remaining region: Region 2.
Now, we take the union of ∼L (Region 2) and R (Region 4). We are left with the set of Regions 2 and 4.
The Final Revelation
Look closely at Regions 2 and 4. Region 2 is where both P and Q are true, and Region 4 is where both P and Q are false. This is the definition of the Biconditional statement, P↔Q.
We have successfully reduced a complex logical expression into a beautiful, symmetric statement. We now compare this to the provided options.
Option 1 is
((∼P)∨Q)∧((∼Q)∨P). This is equivalent to:
(P⇒Q)∧(Q⇒P)
This is the standard definition of P↔Q. We have arrived at the truth.
Remember, in JEE Advanced, the math is just a language. Once you learn to speak it fluently, you don't solve problems; you simply observe the truth unfolding.