2 Overview
The syntax of a language comprises two sets of rules for the use of symbols in it:
- the formation of formulas; and
- the transformation of formulas.
2.1 Strings and formulas
A formula is a certain sort of string of symbols.
A string of symbols is an ordered set of symbols. A string of symbols in a language is a string of symbols in the alphabet of that language.
A string is well-ordered, or a formula, if it is constructed in accordance with certain rules, called rules of formation, or rules for the construction of well-formed formulas, or wffs.
2.2 Rules of formation
SL and FOL have overlapping but different rules for the construction of wffs. These are outlined respectively in:
2.3 Rules of transformation
SL and FOL have also overlapping but different rules for the transformation of formulas. These rules govern a natural-deduction proof system for each language, which is outlined in: