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Boolean Theorems Overview

Aug 27, 2025

Overview

This lecture covers three key theorems in Boolean algebra: the Uniting Theorem, the Elimination Theorem, and the Absorption Theorem, with a focus on their statements, dual forms, and proofs.

Uniting Theorem

  • The theorem states: X AND (Y OR Y') = X.
  • The dual form: X OR (Y AND Y') = X.
  • Proof uses the fact that (Y OR Y') = 1 and (Y AND Y') = 0.
  • Factoring X in expressions simplifies terms to X.

Elimination Theorem

  • The theorem states: X OR (X' AND Y) = X OR Y.
  • The dual form: X AND (X' OR Y) = X AND Y.

Absorption Theorem

  • The theorem states: X OR (X AND Y) = X.
  • The dual form: X AND (X OR Y) = X.

Key Terms & Definitions

  • Dual — The form of a Boolean statement after interchanging AND (â‹…) and OR (+) and swapping 0 and 1.
  • Prime (') — Indicates logical NOT or complement (e.g., X' means NOT X).
  • Absorption — Boolean rule where combining a term with its conjunction/disjunction yields the original term.

Action Items / Next Steps

  • Review and practice applying these theorems to simplify Boolean expressions.
  • Prepare to use these rules in upcoming logic circuit problems.