Predicate Variable
In mathematical logic, a predicate variable is a predicate letter which functions as a "placeholder" for a relation (between terms), but which has not been specifically assigned any particular relation (or meaning). Common symbols for denoting predicate variables include capital roman letters such as P, Q and R, or lower case roman letters, e.g., x. In firstorder logic, they can be more properly called metalinguistic variables. In higherorder logic, predicate variables correspond to propositional variables which can stand for wellformed formulas of the same logic, and such variables can be quantified by means of (at least) secondorder quantifiers. Notation Predicate variables should be distinguished from predicate constants, which could be represented either with a different (exclusive) set of predicate letters, or by their own symbols which really do have their own specific meaning in their domain of discourse: e.g. =, \ \in , \ \le,\ <, \ \sub,... . If letters a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] 

Mathematical Logic
Mathematical logic is the study of formal logic within mathematics. Major subareas include model theory, proof theory, set theory, and recursion theory. Research in mathematical logic commonly addresses the mathematical properties of formal systems of logic such as their expressive or deductive power. However, it can also include uses of logic to characterize correct mathematical reasoning or to establish foundations of mathematics. Since its inception, mathematical logic has both contributed to and been motivated by the study of foundations of mathematics. This study began in the late 19th century with the development of axiomatic frameworks for geometry, arithmetic, and analysis. In the early 20th century it was shaped by David Hilbert's program to prove the consistency of foundational theories. Results of Kurt Gödel, Gerhard Gentzen, and others provided partial resolution to the program, and clarified the issues involved in proving consistency. Work in set theory sho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] 

Latin Script
The Latin script, also known as Roman script, is an alphabetic writing system based on the letters of the classical Latin alphabet, derived from a form of the Greek alphabet which was in use in the ancient Greek city of Cumae, in southern Italy ( Magna Grecia). It was adopted by the Etruscans and subsequently by the Romans. Several Latinscript alphabets exist, which differ in graphemes, collation and phonetic values from the classical Latin alphabet. The Latin script is the basis of the International Phonetic Alphabet, and the 26 most widespread letters are the letters contained in the ISO basic Latin alphabet. Latin script is the basis for the largest number of alphabets of any writing system and is the most widely adopted writing system in the world. Latin script is used as the standard method of writing for most Western and Central, and some Eastern, European languages as well as many languages in other parts of the world. Name The script is either called Latin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] 

Firstorder Logic
Firstorder logic—also known as predicate logic, quantificational logic, and firstorder predicate calculus—is a collection of formal systems used in mathematics, philosophy, linguistics, and computer science. Firstorder logic uses quantified variables over nonlogical objects, and allows the use of sentences that contain variables, so that rather than propositions such as "Socrates is a man", one can have expressions in the form "there exists x such that x is Socrates and x is a man", where "there exists''"'' is a quantifier, while ''x'' is a variable. This distinguishes it from propositional logic, which does not use quantifiers or relations; in this sense, propositional logic is the foundation of firstorder logic. A theory about a topic is usually a firstorder logic together with a specified domain of discourse (over which the quantified variables range), finitely many functions from that domain to itself, finitely many predicates defined on that domain, and a set of a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] 

Metalinguistic Variable
In logic, a metavariable (also metalinguistic variable or syntactical variable) is a symbol or symbol string which belongs to a metalanguage and stands for elements of some object language. For instance, in the sentence :''Let A and B be two sentences of a language ℒ'' the symbols A and B are part of the metalanguage in which the statement about the object language ℒ is formulated. John Corcoran considers this terminology unfortunate because it obscures the use of schemata and because such "variables" do not actually range over a domain. The convention is that a metavariable is to be uniformly substituted with the same instance in all its appearances in a given schema. This is in contrast with nonterminal symbols in formal grammars where the nonterminals on the right of a production can be substituted by different instances.. Attempts to formalize the notion of metavariable result in some kind of type theory.Masahiko Sato, Takafumi Sakurai, Yukiyoshi Kameyama, and Atsushi I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] 

Higherorder Logic
mathematics and logic, a higherorder logic is a form of predicate logic that is distinguished from firstorder logic by additional quantifiers and, sometimes, stronger semantics. Higherorder logics with their standard semantics are more expressive, but their modeltheoretic properties are less wellbehaved than those of firstorder logic. The term "higherorder logic", abbreviated as HOL, is commonly used to mean higherorder simple predicate logic. Here "simple" indicates that the underlying type theory is the ''theory of simple types'', also called the ''simple theory of types'' (see Type theory). Leon Chwistek and Frank P. Ramsey proposed this as a simplification of the complicated and clumsy ''ramified theory of types'' specified in the ''Principia Mathematica'' by Alfred North Whitehead and Bertrand Russell. ''Simple types'' is nowadays sometimes also meant to exclude polymorphic and dependent types. Quantification scope Firstorder logic quantifies only variables ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] 

Propositional Variable
In mathematical logic, a propositional variable (also called a sentential variable or sentential letter) is an input variable (that can either be true or false) of a truth function. Propositional variables are the basic buildingblocks of propositional formulas, used in propositional logic and higherorder logics. Uses Formulas in logic are typically built up recursively from some propositional variables, some number of logical connectives, and some logical quantifiers. Propositional variables are the atomic formulas of propositional logic, and are often denoted using capital roman letters such as P, Q and R. ;Example In a given propositional logic, a formula can be defined as follows: * Every propositional variable is a formula. * Given a formula ''X'', the negation ''¬X'' is a formula. * Given two formulas ''X'' and ''Y'', and a binary connective ''b'' (such as the logical conjunction ∧),the expression ''(X b Y)'' is a formula. (Note the parentheses.) Through this co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] 

Wellformed Formula
In mathematical logic, propositional logic and predicate logic, a wellformed formula, abbreviated WFF or wff, often simply formula, is a finite sequence of symbols from a given alphabet that is part of a formal language. A formal language can be identified with the set of formulas in the language. A formula is a syntactic object that can be given a semantic meaning by means of an interpretation. Two key uses of formulas are in propositional logic and predicate logic. Introduction A key use of formulas is in propositional logic and predicate logic such as firstorder logic. In those contexts, a formula is a string of symbols φ for which it makes sense to ask "is φ true?", once any free variables in φ have been instantiated. In formal logic, proofs can be represented by sequences of formulas with certain properties, and the final formula in the sequence is what is proven. Although the term "formula" may be used for written marks (for instance, on a piece of paper ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] 

Quantifier (logic)
In logic, a quantifier is an operator that specifies how many individuals in the domain of discourse satisfy an open formula. For instance, the universal quantifier \forall in the first order formula \forall x P(x) expresses that everything in the domain satisfies the property denoted by P. On the other hand, the existential quantifier \exists in the formula \exists x P(x) expresses that there exists something in the domain which satisfies that property. A formula where a quantifier takes widest scope is called a quantified formula. A quantified formula must contain a bound variable and a subformula specifying a property of the referent of that variable. The mostly commonly used quantifiers are \forall and \exists. These quantifiers are standardly defined as duals; in classical logic, they are interdefinable using negation. They can also be used to define more complex quantifiers, as in the formula \neg \exists x P(x) which expresses that nothing has the property P. Ot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] 

Domain Of Discourse
In the formal sciences, the domain of discourse, also called the universe of discourse, universal set, or simply universe, is the set of entities over which certain variables of interest in some formal treatment may range. Overview The domain of discourse is usually identified in the preliminaries, so that there is no need in the further treatment to specify each time the range of the relevant variables. Many logicians distinguish, sometimes only tacitly, between the ''domain of a science'' and the ''universe of discourse of a formalization of the science''.José Miguel Sagüillo, Domains of sciences, universe of discourse, and omega arguments, History and philosophy of logic, vol. 20 (1999), pp. 267–280. Examples For example, in an interpretation of firstorder logic, the domain of discourse is the set of individuals over which the quantifiers range. A proposition such as is ambiguous, if no domain of discourse has been identified. In one interpretation, the domain of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] 

Axiom Schema
In mathematical logic, an axiom schema (plural: axiom schemata or axiom schemas) generalizes the notion of axiom. Formal definition An axiom schema is a formula in the metalanguage of an axiomatic system, in which one or more schematic variables appear. These variables, which are metalinguistic constructs, stand for any term or subformula of the system, which may or may not be required to satisfy certain conditions. Often, such conditions require that certain variables be free, or that certain variables not appear in the subformula or term. Finite axiomatization Given that the number of possible subformulas or terms that can be inserted in place of a schematic variable is countably infinite, an axiom schema stands for a countably infinite set of axioms. This set can usually be defined recursively. A theory that can be axiomatized without schemata is said to be finitely axiomatized. Theories that can be finitely axiomatized are seen as a bit more metamathematically elegant, even ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] 

Arity
Arity () is the number of arguments or operands taken by a function, operation or relation in logic, mathematics, and computer science. In mathematics, arity may also be named ''rank'', but this word can have many other meanings in mathematics. In logic and philosophy, it is also called adicity and degree. In linguistics, it is usually named valency. Examples The term "arity" is rarely employed in everyday usage. For example, rather than saying "the arity of the addition operation is 2" or "addition is an operation of arity 2" one usually says "addition is a binary operation". In general, the naming of functions or operators with a given arity follows a convention similar to the one used for ''n''based numeral systems such as binary and hexadecimal. One combines a Latin prefix with the ary ending; for example: * A nullary function takes no arguments. ** Example: f()=2 * A unary function takes one argument. ** Example: f(x)=2x * A binary function takes two arguments. ** E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] 

Propositional Logic
Propositional calculus is a branch of logic. It is also called propositional logic, statement logic, sentential calculus, sentential logic, or sometimes zerothorder logic. It deals with propositions (which can be true or false) and relations between propositions, including the construction of arguments based on them. Compound propositions are formed by connecting propositions by logical connectives. Propositions that contain no logical connectives are called atomic propositions. Unlike firstorder logic, propositional logic does not deal with nonlogical objects, predicates about them, or quantifiers. However, all the machinery of propositional logic is included in firstorder logic and higherorder logics. In this sense, propositional logic is the foundation of firstorder logic and higherorder logic. Explanation Logical connectives are found in natural languages. In English for example, some examples are "and" ( conjunction), "or" (disjunction), "not" (negation) and "if" ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] 