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  2. Grzegorczyk hierarchy - Wikipedia

    en.wikipedia.org/wiki/Grzegorczyk_hierarchy

    Every function in the Grzegorczyk hierarchy is a primitive recursive function, and every primitive recursive function appears in the hierarchy at some level. The hierarchy deals with the rate at which the values of the functions grow; intuitively, functions in lower levels of the hierarchy grow slower than functions in the higher levels.

  3. Nicod's axiom - Wikipedia

    en.wikipedia.org/wiki/Nicod's_axiom

    In logic, Nicod's axiom (named after the French logician and philosopher Jean Nicod) is a formula that can be used as the sole axiom of a semantically complete system of propositional calculus. The only connective used in the formulation of Nicod's axiom is the Sheffer's stroke. The axiom has the following form:

  4. Primitive notion - Wikipedia

    en.wikipedia.org/wiki/Primitive_notion

    In mathematics, logic, philosophy, and formal systems, a primitive notion is a concept that is not defined in terms of previously-defined concepts. It is often motivated informally, usually by an appeal to intuition and everyday experience. In an axiomatic theory, relations between primitive notions are restricted by axioms. [1]

  5. Craig's theorem - Wikipedia

    en.wikipedia.org/wiki/Craig's_theorem

    In mathematical logic, Craig's theorem (also known as Craig's trick [1]) states that any recursively enumerable set of well-formed formulas of a first-order language is (primitively) recursively axiomatizable. This result is not related to the well-known Craig interpolation theorem, although both results are named after the same logician ...

  6. Jean Nicod - Wikipedia

    en.wikipedia.org/wiki/Jean_Nicod

    Jean George Pierre Nicod (1 June 1893, in France – 16 February 1924, in Geneva, Switzerland) was a French philosopher and logician, best known for his work on propositional logic and induction. Biography

  7. Gentzen's consistency proof - Wikipedia

    en.wikipedia.org/wiki/Gentzen's_consistency_proof

    Gentzen's consistency proof is a result of proof theory in mathematical logic, published by Gerhard Gentzen in 1936. It shows that the Peano axioms of first-order arithmetic do not contain a contradiction (i.e. are "consistent"), as long as a certain other system used in the proof does not contain any contradictions either.

  8. Gödel's incompleteness theorems - Wikipedia

    en.wikipedia.org/wiki/Gödel's_incompleteness...

    Gödel's incompleteness theorems are two theorems of mathematical logic that are concerned with the limits of provability in formal axiomatic theories. These results, published by Kurt Gödel in 1931, are important both in mathematical logic and in the philosophy of mathematics.

  9. Predicate functor logic - Wikipedia

    en.wikipedia.org/wiki/Predicate_functor_logic

    In mathematical logic, predicate functor logic (PFL) is one of several ways to express first-order logic (also known as predicate logic) by purely algebraic means, i.e., without quantified variables. PFL employs a small number of algebraic devices called predicate functors (or predicate modifiers ) [ 1 ] that operate on terms to yield terms.