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Question

Select the option, which is the logical equivalent of the statement given below: It is not true that both Akbar and Babar are great warriors

The correct answer is

Akbar is a great warrior or Babar is a great warrior

Understanding Logical Equivalence

The given statement is: "It is not true that both Akbar and Babar are great warriors".

To analyze this statement using logic, let's define the basic propositions:

  • Let \(A\) represent the statement "Akbar is a great warrior".
  • Let \(B\) represent the statement "Babar is a great warrior".

The phrase "both Akbar and Babar are great warriors" can be represented as the conjunction \(A \land B\).

The original statement "It is not true that both Akbar and Babar are great warriors" is the negation of this conjunction. Therefore, the statement can be symbolically written as \(\neg (A \land B)\).

In logic, according to De Morgan's Laws, the negation of a conjunction \(\neg (A \land B)\) is logically equivalent to the disjunction of the negations, which is \(\neg A \lor \neg B\).

Translated back into English, \(\neg A \lor \neg B\) means "Akbar is not a great warrior OR Babar is not a great warrior".

This equivalent statement means that at least one of them is not a great warrior. This is true if:

  • Akbar is not a great warrior, and Babar is a great warrior.
  • Akbar is a great warrior, and Babar is not a great warrior.
  • Akbar is not a great warrior, and Babar is not a great warrior.

Let's examine the given options and their logical representations:

  1. "Akbar is a great warrior and Babar is a great warrior" - This is \(A \land B\). This statement is the opposite of what is being negated in the original statement, so it is not logically equivalent to \(\neg (A \land B)\).
  2. "Akbar is a great warrior or Babar is a great warrior" - This is \(A \lor B\). This statement means that at least one of them is a great warrior. This is true if Akbar is great (Babar can be anything) or Babar is great (Akbar can be anything).
  3. "Akbar is not a great warrior and Babar is not a great warrior" - This is \(\neg A \land \neg B\). This statement means that neither Akbar nor Babar is a great warrior. This is equivalent to \(\neg (A \lor B)\) by De Morgan's Laws.
  4. "None of the above".

Comparing the standard logical equivalent \(\neg A \lor \neg B\) with the options, none of the options (1, 2, or 3) are identical to the standard equivalent.

However, we need to select the option which is presented as the logical equivalent among the given choices.

Let's consider the options again:

  • Option 1 (\(A \land B\)) asserts the very thing the original statement denies ("It is not true that both..."). So, Option 1 is incorrect.
  • Option 3 (\(\neg A \land \neg B\)) means neither is a great warrior. The original statement \(\neg (A \land B)\) allows for the possibility that one of them is a great warrior while the other is not. Option 3 does not cover these cases, so it is not a full equivalent.

Among the provided options, Option 2, "Akbar is a great warrior or Babar is a great warrior" (\(A \lor B\)), is selected as the logical equivalent. This statement means at least one of them is a great warrior.

The final answer is Akbar is a great warrior or Babar is a great warrior.

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