Ordinal de Feferman-Schütte — En mathématiques, et plus précisément en théorie des ensembles, l’ordinal de Feferman–Schütte, noté Γ0, est un grand ordinal dénombrable, étudié par Solomon Feferman (en) et Kurt Schütte (en). Définition L … Wikipédia en Français
Ordinal collapsing function — In mathematical logic and set theory, an ordinal collapsing function (or projection function) is a technique for defining (notations for) certain recursive large countable ordinals, whose principle is to give names to certain ordinals much larger … Wikipedia
Ordinal notation — In mathematical logic and set theory, an ordinal notation is a finite sequence of symbols from a finite alphabet which names an ordinal number according to some scheme which gives meaning to the language. There are many such schemes of ordinal… … Wikipedia
Ordinal analysis — In proof theory, ordinal analysis assigns ordinals (often large countable ordinals) to mathematical theories as a measure of their strength. The field was formed when Gerhard Gentzen in 1934 used cut elimination to prove, in modern terms, that… … Wikipedia
Ordinal number — This article is about the mathematical concept. For number words denoting a position in a sequence ( first , second , third , etc.), see Ordinal number (linguistics). Representation of the ordinal numbers up to ωω. Each turn of the spiral… … Wikipedia
Large countable ordinal — In the mathematical discipline of set theory, there are many ways of describing specific countable ordinals. The smallest ones can be usefully and non circularly expressed in terms of their Cantor normal forms. Beyond that, many ordinals of… … Wikipedia
Kurt Schütte — 14 October 1909 (Salzwedel) ndash; 18 August 1998 was a German mathematician who worked on proof theory and ordinal analysis. The Feferman Schütte ordinal, which he showed to be the precise ordinal bound for predicativity, is named after… … Wikipedia
Church–Kleene ordinal — In mathematics, the Church–Kleene ordinal, , is a large countable ordinal. It is the smallest non recursive ordinal. It is named after Alonzo Church and S. C. Kleene. References Church, Alonzo; Kleene, S. C. (1937), Formal definitions in the… … Wikipedia
Small Veblen ordinal — In mathematics, the small Veblen ordinal is a certain large countable ordinal, named after Oswald Veblen. It is occasionally called the Ackermann ordinal, though the Ackermann ordinal described by harvtxt|Ackermann|1951 is somewhat smaller than… … Wikipedia
Ackermann ordinal — In mathematics, the Ackermann ordinal is a certain large countable ordinal, named after Wilhelm Ackermann. The term Ackermann ordinal is also occasionally used for the small Veblen ordinal, a somewhat larger ordinal. Unfortunately there is no… … Wikipedia
