**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

**Normal form (natural deduction)** — An inference of natural deduction is a normal form, according to Dag Prawitz, if no formula occurrence is both the principal premise of an elimination rule and the conclusion of an introduction rule. This logic related article is a stub. You can… … Wikipedia

**Deduction** — may refer to: in logic: Deductive reasoning, inference in which the conclusion is of no greater generality than the premises Natural deduction, an approach to proof theory that attempts to provide a formal model of logical reasoning as it… … Wikipedia

**Deduction theorem** — In mathematical logic, the deduction theorem is a metatheorem of first order logic.[1] It is a formalization of the common proof technique in which an implication A → B is proved by assuming A and then proving B from this assumption.… … Wikipedia

**natural** — I. adjective Etymology: Middle English, from Anglo French naturel, from Latin naturalis of nature, from natura nature Date: 14th century 1. based on an inherent sense of right and wrong < natural justice > 2. a. being in accordance with or… … New Collegiate Dictionary

**Deduction** — • An argument or reasoning process, that kind of mediate inference by which from truths already known we advance to a knowledge of other truths necessarily implied in the former; the mental product or result of that process. Also a method, the… … Catholic encyclopedia

**natural law** — a principle or body of laws considered as derived from nature, right reason, or religion and as ethically binding in human society. Cf. positive law. [1350 1400; ME] * * * In jurisprudence and political philosophy, a system of right or justice… … Universalium

**Natural language understanding** — Learning to read by Sigurður málari, 19th century. Natural language understanding is a subtopic of natural language processing in artificial intelligence that deals with machine reading comprehension. The proc … Wikipedia

**Natural resources consumption tax** — Taxation An aspect of fiscal policy … Wikipedia

**Hilbert-style deduction system** — In logic, especially mathematical logic, a Hilbert style deduction system is a type of system of formal deduction attributed to Gottlob FregeMáté Ruzsa 1997:129] and David Hilbert. These deductive systems are most often studied for first order… … Wikipedia