Definition:Language of Propositional Logic/Alphabet/Sign/Bracket
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The signs of the language of propositional logic include the brackets:
|\(\ds \bullet \ \ \)||\(\ds (\)||\(:\)||\(\ds \)the left bracket sign\(\)|
|\(\ds \bullet \ \ \)||\(\ds )\)||\(:\)||\(\ds \)the right bracket sign\(\)|
These are used as parenthesis signs.
Also defined as
Some sources use square brackets: $[$ and $]$ instead of the round brackets $($ and $)$. No doubt there are sources which use a different shape. The choice is arbitrary.
Some treatments of propositional logic do not specify brackets at all, having constructed the rules of formation to make them unnecessary.
- 1965: E.J. Lemmon: Beginning Logic ... (previous) ... (next): Chapter $2$: The Propositional Calculus $2$: $1$ Formation Rules
- 1996: H. Jerome Keisler and Joel Robbin: Mathematical Logic and Computability ... (previous) ... (next): $\S 1.2$: Syntax of Propositional Logic