Propositional Logic 2 Flashcards
Logical equivalence means…
compund propositions have the same truth value.
What are the 4 related implications?
- Direct
- Contrapositive
- Inverse
- Converse
If pvq (direct), what is its contrapositive?
~qv~p.
If pvq (direct), what is its inverse?
~pv~q.
If pvq (direct), what is its converse?
qvp.
What is a contrapositive’s relationship to the direct proposition?
It is equivalent to the direct.
What is an inverse’s relationship to the direct proposition?
It is not equivalent to the direct.
What is a converse’s relationship to the inverse proposition?
It is equivalent to the inverse.
What is De Morgan’s Negation of Conjunction?
~pv~q ≡ ~(p^q).
What is De Morgan’s Negation of Disjunction?
~p^~q ≡ ~(pvq).
What are the 3 basic laws and 3 properties of logical equivalence?
- Identity Law
- Domination Rule
- Idempotent Law
- Double Negation
- Commutative
- Associative
What are the 4 advanced laws of logical equivalence?
- Distributive
- De Morgan’s
- Absorption
- Negation/Complement
Identity Law states that…
combining a proposition with the logical identity element (T or F) doesn’t change the value of the proposition when F is used with (v) and T for (^).
Write the Identity Law in symbols.
pvF ≡ p;
p^T ≡ p.
Domination Rule states that…
if you have a proposition and an identity element (T or F) combined with either logical (v) or logical (^), the result is always true for (v) and false for (^).
The combinations in Domination Rule can either be a…
tautology or contradiction.
Write the Domination Rule in symbols.
pvT ≡ T;
p^F ≡ F.
Idempotent Law refers to a property of…
certain operations or functions where applying the operation multiple times doesn’t change the result after the first application.
Write the Idempotent Law in symbols.
pvp ≡ p;
p^p ≡ p.
The property of Double Negation states that…
not not p and p have the same truth value.