Σ-Preorderings in ℍF (ℝ). / Morozov, A. S.
In: Algebra and Logic, Vol. 58, No. 5, 01.11.2019, p. 405-416.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - Σ-Preorderings in ℍF (ℝ)
AU - Morozov, A. S.
PY - 2019/11/1
Y1 - 2019/11/1
N2 - It is proved that the ordinal ω1cannot be embedded into a preordering Σ-definable with parameters in the hereditarily finite superstructure over the real numbers. As a corollary, we obtain the descriptions of ordinals Σ-presentable overℍF(ℝ) and of Gödel constructive sets of the form Lα. It is also shown that there are no Σ-presentations of structures of T-, m-, 1- and tt-degrees.
AB - It is proved that the ordinal ω1cannot be embedded into a preordering Σ-definable with parameters in the hereditarily finite superstructure over the real numbers. As a corollary, we obtain the descriptions of ordinals Σ-presentable overℍF(ℝ) and of Gödel constructive sets of the form Lα. It is also shown that there are no Σ-presentations of structures of T-, m-, 1- and tt-degrees.
KW - Hereditarily finite superstructure
KW - Ordinal
KW - Real numbers
KW - Σ-definable preordering
KW - Sigma-definable preordering
KW - DEFINABILITY
KW - NONPRESENTABILITY
UR - http://www.scopus.com/inward/record.url?scp=85076336469&partnerID=8YFLogxK
U2 - 10.1007/s10469-019-09560-0
DO - 10.1007/s10469-019-09560-0
M3 - Article
AN - SCOPUS:85076336469
VL - 58
SP - 405
EP - 416
JO - Algebra and Logic
JF - Algebra and Logic
SN - 0002-5232
IS - 5
ER -
ID: 22997247