Definition:Formal System
Definition
A formal system is a formal language $\LL$ together with a deductive apparatus for $\LL$.
Let $\FF$ be a formal system consisting of a formal language with deductive apparatus $\DD$.
By applying the formal grammar of $\LL$, one constructs well-formed formulae in $\LL$.
Of such a well-formed formula, one can then use the deductive apparatus $\DD$ to determine whether or not it is a theorem in $\FF$.
Also known as
A formal system is also known as:
particularly in sources where the main application of formal systems lies in symbolic logic.
On $\mathsf{Pr} \infty \mathsf{fWiki}$, these terms are discouraged because they provoke false conclusions about the scope of the term formal system.
Some sources use the term axiomatic system, particularly when applying this technique to specific fields of mathematics.
Also see
- Definition:Symbolic Logic, which is an important field of application for formal systems.
- Results about formal systems can be found here.
Sources
- 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): formal system (formal theory)
- 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): formal system (formal theory)
- 2014: Christopher Clapham and James Nicholson: The Concise Oxford Dictionary of Mathematics (5th ed.) ... (previous) ... (next): axiomatic system