Formal Notation
The disjunction introduction rule may be written in sequent notation:
where is a metalogical symbol meaning that is a syntactic consequence of in some logical system;
and expressed as a truth-functional tautology or theorem of propositional logic:
where and are propositions expressed in some formal system.
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Famous quotes containing the word formal:
“The bed is now as public as the dinner table and governed by the same rules of formal confrontation.”
—Angela Carter (1940–1992)