1  Alphabet

The alphabet of a language is the set of symbols used in it.

1.1 SL alphabet

The alphabet of SL is comprised of three sorts of symbol:

• Upper-case letters, with or without numerical subscripts (e.g., \(A, B, A_{1}, A_{23},\) etc.)
• Logical connectives \(\neg, \vee, \wedge, \to, \leftrightarrow\)
• (Parentheses) and [brackets]

1.2 FOL alphabet

The alphabet of FOL is comprised of all of the symbols in SL and, in addition:

• Quantifiers \(\forall\) and \(\exists\)
• Lower-case letters \(a \ldots z\)