This article is cited in 32 papers

$\Delta_2^0$-Copies of Linear Orderings

A. N. Frolov

Kazan State University

Abstract: It is proved that, for any $n\in\omega$, there exist countable linear orderings $L_n$ whose $\Delta_2^0$-spectrum consists of exactly all non $n$-low $\Delta_2^0$-degrees. Properties of such orderings are examined, for $n=1$ and $n=2$.

Keywords: countable linear ordering, $\Delta_2^0$-degree, $\Delta_2^0$-spectrum.

UDC: 510.53+512.562

Received: 08.09.2004
Revised: 12.12.2005

 English version: Algebra and Logic, 2006, 45:3, 201–209

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