Results 51 to 60 of about 166,162,676 (139)

A note on $\mathbb{Z}$ as a direct summand of nonstandard models of weak systems of arithmetic

open access: yes, 2016
There are nonstandard models of normal open induction ($NOI$) for which $\mathbb{Z}$ is a direct summand of their additive group. We show that this is impossible for nonstandard models of $IE_2$.
openaire   +2 more sources

Initial segments and end-extensions of models of arithmetic [PDF]

open access: yes, 2010
This thesis is organized into two independent parts. In the first part, we extend the recent work on generic cuts by Kaye and the author. The focus here is the properties of the pairs (M, I) where I is a generic cut of a model M.
Wong, Tin Lok
core   +1 more source

Constructive Nonstandard Models for Peano Arithmetic

open access: yes
This paper explores the notion of constructive nonstandard models for Peano Arithmetic (PA). While classical model theory provides a rich landscape of nonstandard models, their existence often relies on non-constructive principles such as the Axiom of Choice or the Compactness Theorem.
openaire   +1 more source

On automorphisms of models of Peano arithmetic

open access: yes, 2004
When studying the automorphism group Aut(M) of a model M, one is interested to what extent M is recoverable from Aut(M). We show that if M is a countable arithmetically saturated of Peano Arithmetic, then Aut(M) can recognize if a maximal open subgroup ...
Nurkhaidarov, Ermek S
core   +1 more source

COMPUTABLE QUOTIENT PRESENTATIONS OF MODELS OF ARITHMETIC AND SET THEORY (Mathematical Logic and Its Applications) [PDF]

open access: yes, 2017
We prove various extensions of the Tennenbaum phenomenon to the case of computable quotient presentations of models of arithmetic and set theory.
Hamkins, Joel David   +1 more
core  

The Fine Structure Theory of Nonstandard Models of Peano Arithmetic

open access: yes
This paper delves into the fine structure theory of nonstandard models of Peano Arithmetic (PA). Nonstandard models provide a rich landscape for exploring foundational issues in arithmetic, extending beyond the intuitive standard model of natural numbers.
openaire   +3 more sources

Non-standard discretization of biological models [PDF]

open access: yes, 2015
We consider certain types of discretization schemes for differential equations with quadratic nonlinearities, which were introduced by Kahan, and considered in a broader setting by Mickens.
Towler, Kim, Hone, Andrew N.W.
core  

Human verifications: Computable with truth values outside logic. [PDF]

open access: yesProc Natl Acad Sci U S A, 2023
Johnson-Laird PN   +2 more
europepmc   +1 more source

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