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.