Kaasaegne teaduslik mõtlemine ja filosoofilised meetodid
Let the two propositions be P and Q:
P implies Q or Q implies P
(P → Q) v (Q → P)
Well-formed formulas
An expression i well-formed if the arrangement of its words is syntactically correct.
I know that Tallinn is the Capital of Estonia (correct)
I know that Tartu is the Capital of Estonia (correct)
Capital know Tallinn the I Estonia is of (uncorrect)
Similarly, a formula is well-formed if the arrangement of its symbols is syntactiacally correct.
3+(5x2)=8 (correct)
3+(5x)2=8 (uncorrect)
P→ (Q v ¬ R) (correct)
P ¬ → (Q v R) (uncorrect)
Truth values
Propositions are either true or false.
Truth and falsity are Truth-values.
The truth -value of simple proposition is not the business of propositional logic.
The truth-value of compound propositions is determined by propositional logic.
It depends on the truth-values of the simple propositions that compose it and the connectives that
connect them.
Example:
annaabi.ee 
