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  2. Double negation - Wikipedia

    en.wikipedia.org/wiki/Double_negation

    Double negation elimination and double negation introduction are two valid rules of replacement. They are the inferences that, if not not-A is true, then A is true, and its converse, that, if A is true, then not not-A is true, respectively. The rule allows one to introduce or eliminate a negation from a formal proof.

  3. Intuitionistic logic - Wikipedia

    en.wikipedia.org/wiki/Intuitionistic_logic

    In particular, systems of intuitionistic logic do not assume the law of the excluded middle and double negation elimination, which are fundamental inference rules in classical logic. Formalized intuitionistic logic was originally developed by Arend Heyting to provide a formal basis for L. E. J. Brouwer's programme of intuitionism.

  4. Negation - Wikipedia

    en.wikipedia.org/wiki/Negation

    One obtains the rules for intuitionistic negation the same way but by excluding double negation elimination. Negation introduction states that if an absurdity can be drawn as conclusion from then must not be the case (i.e. is false (classically) or refutable (intuitionistically) or etc.). Negation elimination states that anything follows from ...

  5. Negation introduction - Wikipedia

    en.wikipedia.org/wiki/Negation_introduction

    Negation introduction is a rule of inference, or transformation rule, in the field of propositional calculus. Negation introduction states that if a given antecedent implies both the consequent and its complement, then the antecedent is a contradiction.

  6. Markov's principle - Wikipedia

    en.wikipedia.org/wiki/Markov's_principle

    Download as PDF; Printable version; ... Markov's rule is the formulation of Markov's principle as a rule. ... Assuming classical double-negation elimination, the weak ...

  7. List of rules of inference - Wikipedia

    en.wikipedia.org/wiki/List_of_rules_of_inference

    A set of rules can be used to infer any valid conclusion if it is complete, while never inferring an invalid conclusion, if it is sound. A sound and complete set of rules need not include every rule in the following list, as many of the rules are redundant, and can be proven with the other rules.

  8. Heyting arithmetic - Wikipedia

    en.wikipedia.org/wiki/Heyting_arithmetic

    Minimal logic proves double-negation elimination for negated formulas, () (). More generally, Heyting arithmetic proves this classical equivalence for any Harrop formula . And Σ 1 0 {\displaystyle \Sigma _{1}^{0}} -results are well behaved as well: Markov's rule at the lowest level of the arithmetical hierarchy is an admissible rule of ...

  9. Classical logic - Wikipedia

    en.wikipedia.org/wiki/Classical_logic

    Classical logic is the standard logic of mathematics. Many mathematical theorems rely on classical rules of inference such as disjunctive syllogism and the double negation elimination. The adjective "classical" in logic is not related to the use of the adjective "classical" in physics, which has another meaning.