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This article is cited in 5 scientific papers (total in 5 papers)
Ranks for families of permutation theories
N. D. Markhabatov Novosibirsk State Technical University, Novosibirsk, Russian Federation
Abstract:
The notion of rank for families of theories, similar to Morley rank
for fixed theories, serves as a measure of complexity for given
families. There arises a natural problem of describing a rank
hierarchy for a series of families of theories. In this article, we answer the question posed and describe the
ranks and degrees for families of theories of permutations with
different numbers of cycles of a certain length. A number examples
of families of permutation theories that have a finite rank are
given, and it is constructed a family of permutation theories
having a specified countable rank and degree $n$. It is proved
that in the family of permutation theories any theory equals a
theory of a finite structure or it is approximated by finite
structures, i.e. any permutation theory on an infinite set is
pseudofinite. Topological properties of the families under
consideration were studied.
Keywords:
family of theories, pseudofinite theory, permutation, rank, degree.
Received: 25.04.2019
Citation:
N. D. Markhabatov, “Ranks for families of permutation theories”, Bulletin of Irkutsk State University. Series Mathematics, 28 (2019), 85–94
Linking options:
https://www.mathnet.ru/eng/iigum374 https://www.mathnet.ru/eng/iigum/v28/p85
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Abstract page: | 240 | Full-text PDF : | 98 | References: | 21 |
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