# Logic for Computer Scientists/Modal Logic/Syntax

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## Syntax[edit | edit source]

We assume the syntax of classical propositional logic as used in the chapters above. Additional we have the following two rules: If is a formula

are formulae.

The symbols and stand traditionally for *possibility* and
*necessity*; in the context of temporal logic they stand for *always* and
*eventually*, so that stands for * is eventually true* and
for * is always true*.