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In logic and mathematics, a formal system consists of two components, a formal language plus a set of inference rules or transformation rules. A formal system may be formulated purely abstractly, for its own sake, or it may be intended to serve as a description of some domain of real phenomena or some aspect of objective reality. Logic, from Classical Greek λÏÎ³Î¿Ï logos (meaning word, account, reason or principle), is the study of the principles and criteria of valid inference and demonstration. ...
Euclid, Greek mathematician, 3rd century BC, as imagined by by Raphael in this detail from The School of Athens. ...
In mathematics, logic, and computer science, a formal language is a set of finite-length words (i. ...
In logic, especially in mathematical logic, a rule of inference is a scheme for constructing valid inferences. ...
Some theorists use the term formalism as a rough synonym for formal system, but the term is also used to refer to a particular style of notation, for example, Paul Dirac's bra-ket notation. Paul Adrien Maurice Dirac, OM, FRS (IPA: [dɪræk]) (August 8, 1902 â October 20, 1984) was a British theoretical physicist and a founder of the field of quantum physics. ...
Bra-ket notation is the standard notation for describing quantum states in the theory of quantum mechanics. ...
Definition Formal systems in mathematics consist of the following elements: - A finite set of symbols, the alphabet, that can be used for constructing formulas, that is, finite strings of symbols.
- A grammar, which tells how well-formed formulas are constructed out of the symbols in the alphabet. There must be a decision procedure for deciding whether a formula is well formed (a wff) or not.
- A set of axioms or axiom schemata: each axiom must be a wff.
- A set of inference rules.
In order for the formal system to be considered effective, the set of axioms and the set of inference rules must be decidable sets or semidecidable sets, according to context. For the surname, see Grammer. ...
In logic, WFF is an abbreviation for well-formed formula. ...
In logic, especially in mathematical logic, a rule of inference is a scheme for constructing valid inferences. ...
In computability theory a countable set is called recursive, computable or decidable if we can construct an algorithm which terminates after a finite amount of time and decides whether a given element belongs to the set or not. ...
In computability theory, traditionally called recursion theory, a set S of natural numbers is called recursively enumerable, computably enumerable, semidecidable or provable if: There is an algorithm that, when given an input number, eventually halts if and only if the input is an element of S. Or, equivalently, There is...
Formal proofs In mathematics, formal proofs are the product of formal systems, consisting of axioms and rules of deduction. Theorems are then recognized as the possible 'last lines' of formal proofs. The point of view that this sums up all there is to mathematics is often called formalism. David Hilbert founded metamathematics as a discipline for discussing formal systems. Any language that one uses to talk about a formal system is called a metalanguage. The metalanguage may be nothing more than ordinary natural language, or it may be partially formalized itself, but it is generally less completely formalized than the formal language component of the formal system under examination, which is then called the object language, that is, the object of the discussion in question. An axiom is a sentence or proposition that is not proved or demonstrated and is considered as obvious or as an initial necessary consensus for a theory building or acceptation. ...
// Philosophy of mathematics is the branch of philosophy that studies the philosophical assumptions, foundations, and implications of mathematics. ...
David Hilbert (January 23, 1862, Königsberg, East Prussia â February 14, 1943, Göttingen, Germany) was a German mathematician, recognized as one of the most influential and universal mathematicians of the 19th and early 20th centuries. ...
In general, metamathematics or meta-mathematics is reflection about mathematics seen as an entity/object in human consciousness and culture. ...
In logic and linguistics, a metalanguage is a language used to make statements about other languages (object languages). ...
For an account of the concept of object language in mathematical logic, see formal system. ...
Once a formal system is given, one can define the set of theorems which can be proved inside the formal system. This set consists of all the axioms, plus all wffs which can be derived from previously-derived theorems by means of rules of inference. Unlike the grammar for wffs, there is no guarantee that there will be a decision procedure for deciding whether a given wff is a theorem or not. The notion of theorem just defined should not be confused with theorems about the formal system, which, in order to avoid confusion, are usually called metatheorems. A logical system or theory is decidable if the set of all well-formed formulas valid in the system is decidable. ...
In logic, a metatheorem is a statement about theorems or about some axiomatic theory. ...
Reference - S. C. Kleene, 1967. Mathematical Logic Reprinted by Dover, 2002. ISBN 0486425339
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