Abstract
It is proved that, for any n ∈ ω, there exist countable linear orderings Ln whose Δ 02 -spectrum consists of exactly all non n-low Δ 02 -degrees. Properties of such orderings are examined, for n = 1 and n = 2.
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Supported by RFBR grant No. 02-01-00169 and by RF Ministry of Education grant No. E02-1.0-177.
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Translated from Algebra i Logika, Vol. 45, No. 3, pp. 354–370, May–June, 2006.
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Frolov, A.N. Δ 02 -copies of linear orderings. Algebr Logic 45, 201–209 (2006). https://doi.org/10.1007/s10469-006-0017-4
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DOI: https://doi.org/10.1007/s10469-006-0017-4