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JOURNALS // Algebra i logika // Archive

Algebra Logika, 2017 Volume 56, Number 6, Pages 691–711 (Mi al825)

This article is cited in 4 papers

Nonpresentability of some structures of analysis in hereditarily finite superstructures

A. S. Morozovab

a Sobolev Institute of Mathematics, pr. Akad. Koptyuga 4, Novosibirsk, 630090 Russia
b Novosibirsk State University, ul. Pirogova 1, Novosibirsk, 630090 Russia

Abstract: It is proved that any countable consistent theory with infinite models has a $\Sigma$-presentable model of cardinality $2^\omega$ over $\mathbb{HF(R})$. It is shown that some structures studied in analysis (in particular, a semigroup of continuous functions, certain structures of nonstandard analysis, and infinite-dimensional separable Hilbert spaces) have no simple $\Sigma$-presentations in hereditarily finite superstructures over existentially Steinitz structures. The results are proved by a unified method on the basis of a new general sufficient condition.

Keywords: $\Sigma$-presentability, countable consistent theory, hereditarily finite superstructure, existentially Steinitz structure, semigroup of continuous functions, nonstandard analysis, infinite-dimensional separable Hilbert space.

UDC: 510.65

Received: 09.03.2017
Revised: 14.09.2017

DOI: 10.17377/alglog.2017.56.604


 English version:
Algebra and Logic, 2018, 56:6, 458–472

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