Neutral and dominance laws: Difference between revisions

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(Created page with "= Absorption laws = The absorption laws show how certain combinations of conjunction and disjunction can be simplified by "absorbing" one proposition into another. == Statements == * p ∨ (p ∧ q) ≡ p * p ∧ (p ∨ q) ≡ p == Explanation == Adding extra conditions that are already implied by ''p'' does not change the truth value. These laws allow expressions to be reduced in complexity. == Examples == * "I study OR (I study AND I rest)" is logically equivalen...")
 
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= Absorption laws =
= Neutral and dominance laws =


The absorption laws show how certain combinations of conjunction and disjunction can be simplified by "absorbing" one proposition into another.
The neutral and dominance laws describe how conjunction and disjunction interact with the constants ''true'' and ''false''.


== Statements ==
== Neutral laws ==
* p ∨ (p ∧ q) ≡ p
* p ∧ wahr ≡ p
* p ∧ (p ∨ q) ≡ p
* p ∨ falsch ≡ p
 
== Dominance laws ==
* p ∨ wahr wahr
* p ∧ falsch ≡ falsch


== Explanation ==
== Explanation ==
Adding extra conditions that are already implied by ''p'' does not change the truth value.   
* The neutral laws state that combining with the neutral element leaves the proposition unchanged. 
These laws allow expressions to be reduced in complexity.
  – 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 ==
== Examples ==
* "I study OR (I study AND I rest)" is logically equivalent to "I study".
* "I study AND true" "I study".
* "I study AND (I study OR I rest)" is logically equivalent to "I study".
* "I study OR false" ≡ "I study"
 
* "I study OR true" ≡ true.
== Truth Table (First Law) ==
* "I study AND false" ≡ false.
{| class="wikitable"
! p !! q !! p ∧ q !! p ∨ (p ∧ q)
|-
| T || T || T || T
|-
| T || F || F || T
|-
| F || T || F || F
|-
| F || F || F || F
|}


== Truth Table (Second Law) ==
== Truth Tables ==
{| class="wikitable"
{| class="wikitable"
! p !! q !! p ∨ q !! p ∧ (p ∨ q)
! p !! p ∧ wahr !! p ∨ falsch !! p ∨ wahr !! p ∧ falsch
|-
| T || T || T || T
|-
| T || F || T || T
|-
|-
| F || T || T || F
| T || T || T || T || F
|-
|-
| F || F || F || F
| F || F || F || T || F
|}
|}


[[Category:Propositional logic (Aussagenlogik)]]
[[Category:Propositional logic (Aussagenlogik)]]
[[Category: Diskrete Mathematik I (BZG1155pa) 25/26]]
[[Category: Diskrete Mathematik I (BZG1155pa) 25/26]]

Latest revision as of 14:31, 20 October 2025

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