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JOURNALS // Sibirskii Matematicheskii Zhurnal // Archive

Sibirsk. Mat. Zh., 2014 Volume 55, Number 1, Pages 156–164 (Mi smj2521)

This article is cited in 4 papers

Nonpresentability of the semigroup $\omega^\omega$ over $\mathbb{HF(R)}$

A. S. Morozovab

a Sobolev Institute of Mathematics, Novosibirsk, Russia
b Novosibirsk State University, Novosibirsk, Russia

Abstract: We prove that the semigroup of all functions from the set of natural numbers to natural numbers by composition has no one-valued $\Sigma$-presentations with parameters over the hereditarily finite superstructure over the real numbers.

Keywords: definability, computability, sigma-definability, sigma-presentability, semigroup of mappings.

UDC: 510.5

Received: 23.04.2013


 English version:
Siberian Mathematical Journal, 2014, 55:1, 125–131

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© Steklov Math. Inst. of RAS, 2025