Go up to 2.2 Propositional Logic
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Syntactic Forms Logical constants may appear in various forms, e.g. as
The last form is most frequently used; please do not confuse these formulas with the truth values true and false.
Again, please note the distinction between the two layers of syntax (`F', `T') and semantics (true, false).
The Logic Evaluator uses the syntax
true both for (the
input of) logical constants and for (the output of) truth values. However, by
above explanation it should be clear that the input denotes a formula
while the output prefixed by the token `
>' denotes the meaning
of this formula.