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This article is cited in 3 scientific papers (total in 3 papers)
Friedberg numbering of the family of All $\Sigma^{1}_{2}$-sets
M. V. Dorzhieva Novosibirsk State University,
1, Pirogova St., Novosibirsk 630090, Russia
Abstract:
We study the existence of a single-valued $\Sigma^{1}_{2}$-computable enumeration of the family of all $\Sigma^{1}_{2}$-sets. Friedberg proved that there is a numbering of the family of all computably enumerated sets without repetition. The same statement holds for all levels of arithmetical hierarchy, as well as for the Ershov hierarchy. However, J. Owings showed that $\Pi^{1}_{1}$-sets cannot be enumerated without repetition. In this paper, we continue to study the Friedberg numbering in analytical hierarchy. The main result is that there is no Friedberg numbering of the family of all $\Sigma^{1}_{2}$-sets.
Keywords:
enumeration, minimal enumeration, Friedberg enumeration, analytical hierarchy.
Received: 12.12.2013
Citation:
M. V. Dorzhieva, “Friedberg numbering of the family of All $\Sigma^{1}_{2}$-sets”, Sib. J. Pure and Appl. Math., 18:2 (2018), 47–52; J. Math. Sci., 246:6 (2020), 788–792
Linking options:
https://www.mathnet.ru/eng/vngu471 https://www.mathnet.ru/eng/vngu/v18/i2/p47
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Abstract page: | 169 | Full-text PDF : | 41 | References: | 38 | First page: | 7 |
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