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**Logical connective**— This article is about connectives in classical logic. For connectors in natural languages, see discourse connective. For connectives and operators in other logics, see logical constant. For other logical symbols, see table of logic symbols. In… … Wikipedia**logical calculus**— Also called a formal language, and a logistic system. A system in which explicit rules are provided for determining (a) which are the expressions of the system; (b) which sequences of expressions count as well formed ( well formed formulae, or… … Philosophy dictionary**LF (logical framework)**— In type theory, the LF logical framework provides a means to define (or present) logics. It is based on a general treatment of syntax, rules and proofs by means of a dependently typed lambda calculus. Syntax is treated in a style similar to, but… … Wikipedia**Propositional calculus**— In mathematical logic, a propositional calculus or logic (also called sentential calculus or sentential logic) is a formal system in which formulas of a formal language may be interpreted as representing propositions. A system of inference rules… … Wikipedia**Method of analytic tableaux**— A graphical representation of a partially built propositional tableau In proof theory, the semantic tableau (or truth tree) is a decision procedure for sentential and related logics, and a proof procedure for formulas of first order logic. The… … Wikipedia**Natural deduction**— In logic and proof theory, natural deduction is a kind of proof calculus in which logical reasoning is expressed by inference rules closely related to the natural way of reasoning. This contrasts with the axiomatic systems which instead use… … Wikipedia**metalogic**— /met euh loj ik/, n. the logical analysis of the fundamental concepts of logic. [1835 45; META + LOGIC] * * * Study of the syntax and the semantics of formal languages and formal systems. It is related to, but does not include, the formal… … Universalium**Sequent calculus**— In proof theory and mathematical logic, sequent calculus is a family of formal systems sharing a certain style of inference and certain formal properties. The first sequent calculi, systems LK and LJ, were introduced by Gerhard Gentzen in 1934 as … Wikipedia**Multi-valued logic**— Multi valued logics are logical calculi in which there are more than two truth values. Traditionally, logical calculi are two valued that is, there are only two possible truth values (i.e. truth and falsehood) for any proposition to take. An… … Wikipedia**Defeasible reasoning**— is a kind of reasoning that is based on reasons that are defeasible, as opposed to the indefeasible reasons of deductive logic. Defeasible reasoning is a particular kind of non demonstrative reasoning, where the reasoning does not produce a full … Wikipedia