Solution

The correct answer is A-IV, B-II, C-III, D-I.

Key Points

• A. Definite Clause → IV
  • A definite clause has exactly one positive literal.
  • Example: P ← Q ∧ R (or) ¬Q ∨ ¬R ∨ P
• B. Horn Clause → II
  • A Horn clause has at most one positive literal.
  • It includes definite clauses and goal clauses.
• C. Goal Clause → III
  • A goal clause contains no positive literals.
  • Example: ¬P ∨ ¬Q
• D. Inference with Horn Clause → I
  • Horn clauses are solved using Forward Chaining or Backward Chaining.
  • Forward chaining is the standard inference technique.

Additional Information

• Summary:
  • Horn Clause → ≤1 positive literal.
  • Definite Clause → exactly 1 positive literal.
  • Goal Clause → 0 positive literals.
  • Inference → Forward chaining.