Neutral and dominance laws

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Neutral and dominance laws

The neutral and dominance laws describe how conjunction and disjunction interact with the constants true and false.

Neutral laws

  • p ∧ wahr ≡ p
  • p ∨ falsch ≡ p

Dominance laws

  • p ∨ wahr ≡ wahr
  • p ∧ falsch ≡ falsch

Explanation

  • The neutral laws state that combining with the neutral element leaves the proposition unchanged.
 – In conjunction, true is neutral.  
 – In disjunction, false is neutral.  
  • The dominance laws state that combining with the dominant element forces the result.
 – In conjunction, false dominates.  
 – In disjunction, true dominates.  

Examples

  • "I study AND true" ≡ "I study".
  • "I study OR false" ≡ "I study".
  • "I study OR true" ≡ true.
  • "I study AND false" ≡ false.

Truth Tables

p p ∧ wahr p ∨ falsch p ∨ wahr p ∧ falsch
T T T T F
F F F T F