Logical Symbols

Logical Symbols problems involve logical operators (AND, OR, NOT, IMPLIES, IFF, XOR) represented by symbols. You must evaluate logical expressions given the truth values (True/False) of individual propositions.

10Worksheets
200+Practice Questions
IntermediateDifficulty
2-3 hoursHours to Master

Introduction to Logical Symbols

Logical Symbols problems involve logical operators (AND, OR, NOT, IMPLIES, IFF, XOR) represented by symbols. You must evaluate logical expressions given the truth values (True/False) of individual propositions.

Prerequisites

Boolean logic concepts (True/False) AND operator: true only if both true OR operator: true if at least one true NOT operator: flips truth value IMPLIES: false only when P true and Q false XOR: true when inputs differ
Why This Matters: Logical Symbols problems appear in 2-3 questions in Banking PO and SSC exams. They test understanding of logical operations and truth tables.

How to Solve Logical Symbols Problems

1

Step 1: Identify the truth values of each proposition (P, Q, etc.)

2

Step 2: Identify each logical operator and its symbol mapping

3

Step 3: For NOT (!), flip the truth value of the proposition

4

Step 4: For AND (&), result is True only if both operands are True

5

Step 5: For OR (|), result is True if at least one operand is True

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Step 6: For IMPLIES (→), result is False only when P=True and Q=False

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Step 7: For IFF (↔), result is True when both operands are same

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Step 8: For XOR (⊕), result is True when operands are different

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Step 9: Evaluate step by step, using parentheses for grouping

Pro Strategy: Create a truth table mentally for complex expressions. Evaluate innermost parentheses first. Use the truth tables of each operator to guide your evaluation.

Example Problem

Example: If P = True, Q = False, and symbols: & = AND, | = OR, ! = NOT, evaluate: (P & Q) | !P Solution: Step 1: P=True, Q=False Step 2: P & Q = True AND False = False Step 3: !P = NOT True = False Step 4: False | False = False Answer: False

Pro Tips & Tricks

  • AND (&): both must be True for True
  • OR (|): at least one must be True for True
  • NOT (!): flips True↔False
  • IMPLIES (→): only False when P=True and Q=False
  • IFF (↔): True when both same (both True or both False)
  • XOR (⊕): True when different (one True, one False)

Shortcut Methods to Solve Faster

P & False = False
P | True = True
P → Q = ¬P ∨ Q
P ↔ Q = (P → Q) ∧ (Q → P)
P ⊕ Q = (P ∨ Q) ∧ ¬(P ∧ Q)
Double NOT cancels: ¬¬P = P

Common Mistakes to Avoid

Confusing AND with OR
Forgetting that IMPLIES is True when P is False (vacuously true)
Misapplying De Morgan's laws
Not handling parentheses correctly in complex expressions
Confusing XOR with OR

Exam Importance

Logical Symbols is an important topic for various competitive exams. Here's how frequently it appears:

SSC CGL
1-2 questions
BANKING PO
2-3 questions
RAILWAYS RRB
1-2 questions
CAT
2-3 questions
INSURANCE
2-3 questions

Ready to Master Logical Symbols?

Start with Worksheet 1 and work your way up to expert level! Each worksheet includes:

20 practice questions
Detailed solutions
Step-by-step explanations
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