Δ
2
0
-copies of linear orderings |
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| Authors: | A N Frolov |
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| Institution: | (1) Kazan State University, Kazan, Russia |
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| Abstract: | It is proved that, for any n ∈ ω, there exist countable linear orderings Ln whose Δ
2
0
-spectrum consists of exactly all non n-low Δ
2
0
-degrees. Properties of such orderings are examined, for n = 1 and n = 2.
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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| Keywords: | countable linear ordering Δ 2 0 -degree Δ 2 0 -spectrum |
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