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Cuts of real classes

Martin Kalina, Pavol Zlatoš (1989)

Commentationes Mathematicae Universitatis Carolinae

Finite Embeddability of Sets and Ultrafilters

Andreas Blass, Mauro Di Nasso (2015)

Bulletin of the Polish Academy of Sciences. Mathematics

A set A of natural numbers is finitely embeddable in another such set B if every finite subset of A has a rightward translate that is a subset of B. This notion of finite embeddability arose in combinatorial number theory, but in this paper we study it in its own right. We also study a related notion of finite embeddability of ultrafilters on the natural numbers. Among other results, we obtain connections between finite embeddability and the algebraic and topological structure of the Stone-Čech...

Herbrand consistency and bounded arithmetic

Zofia Adamowicz (2002)

Fundamenta Mathematicae

We prove that the Gödel incompleteness theorem holds for a weak arithmetic Tₘ = IΔ₀ + Ωₘ, for m ≥ 2, in the form Tₘ ⊬ HCons(Tₘ), where HCons(Tₘ) is an arithmetic formula expressing the consistency of Tₘ with respect to the Herbrand notion of provability. Moreover, we prove T H C o n s I ( T ) , where H C o n s I is HCons relativised to the definable cut Iₘ of (m-2)-times iterated logarithms. The proof is model-theoretic. We also prove a certain non-conservation result for Tₘ.

Multiplication of nonadditive cuts in AST

Karel Čuda (1991)

Commentationes Mathematicae Universitatis Carolinae

Three complete characteristics of couples of nonadditive cuts such that J × K ̲ J t i m e s K ¯ are given. The equality J × K ¯ = J ! K is proved for all couples of nonadditive cuts. Some examples of nonadditive cuts are described.

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