Compound Negations and De Morgan's Laws
This page introduces the concept of Prawa de Morgana (De Morgan's Laws) and their applications in logic and mathematics.
1 prawo de Morgana (First Law of De Morgan) states that the negation of a disjunction is equivalent to the conjunction of negations:
Definition: ~(p ∨ q) ⇔ (~p) ∧ (~q)
This law demonstrates how the negation of "or" statements can be expressed as "and" statements with negated components.
2 prawo de Morgana (Second Law of De Morgan) states that the negation of a conjunction is equivalent to the disjunction of negations:
Definition: ~(p ∧ q) ⇔ (~p) ∨ (~q)
This law shows how the negation of "and" statements can be expressed as "or" statements with negated components.
The page also covers the negation of implication:
Example: ~(p ⇒ q) ⇔ (p ∧ ~q)
This demonstrates that negating an "if-then" statement is equivalent to asserting the antecedent and negating the consequent.
Lastly, the page introduces quantifiers in logic:
Vocabulary: Quantifiers are symbols used to express the quantity of elements that satisfy a given predicate.
- ∀ represents "for all" or "for every"
- ∃ represents "there exists" or "for some"
These quantifiers are essential in predicate logic and mathematical statements.