### 2.2.1 Logical Constants

The following logical constants are formulas:

**Syntactic Forms**
Logical constants may appear in various forms, e.g. as

- 0, 1;
- "wrong", "right";
- "incorrect", "correct";
- false, true.

The last form is most frequently used; please do not confuse these
*formulas* with the *truth values* __true__ and __false__.

**Definition 4 (Semantics of Logical Constants)**
The *meaning* of `F' is __false__ and the *meaning* of `T' is
__true__.

Again, please note the distinction between the two layers of syntax (`F', `T')
and semantics (__true__, __false__).

The Logic Evaluator uses the syntax `false`

and `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.

Author: Wolfgang Schreiner

Last Modification: October 4, 1999