Zobrazeno 1 - 10
of 21
pro vyhledávání: '"Hristo Ganchev"'
Autor:
Andrey C. Sariev, Hristo Ganchev
Publikováno v:
Archive for Mathematical Logic. 60:909-925
In the present paper, we show the first-order definability of the jump operator in the upper semi-lattice of the $$\omega $$ -enumeration degrees. As a consequence, we derive the isomorphicity of the automorphism groups of the enumeration and the $$\
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::afeadf9b83414f05ad72f5c6553d80c9
https://doi.org/10.1007/s00153-021-00766-7
https://doi.org/10.1007/s00153-021-00766-7
Publikováno v:
The Journal of Symbolic Logic. 87:527-544
We give several new characterizations of the continuous enumeration degrees. The main one proves that an enumeration degree is continuous if and only if it is not half of a nontrivial relativized $\mathcal {K}$ -pair. This leads to a structural dicho
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::5c0ee054218848608aca4077bac7afce
https://doi.org/10.1017/jsl.2019.72
https://doi.org/10.1017/jsl.2019.72
Autor:
Joseph S. Miller, Uri Andrews, Hristo Ganchev, Mariya Ivanova Soskova, Alexandra A. Soskova, Steffen Lempp, Rutger Kuyper
Publikováno v:
Transactions of the American Mathematical Society. 372:1631-1670
A set A ⊆ ω A\subseteq \omega is cototal if it is enumeration reducible to its complement, A ¯ \overline {A} . The skip of A A is the uniform upper bound of the complements of all sets enumeration reducible to A A . These are closely connected: A
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::c07671ed79509599267b40f35b6f7a1c
https://doi.org/10.1090/tran/7604
https://doi.org/10.1090/tran/7604
Autor:
Andrey C. Sariev, Hristo Ganchev
Publikováno v:
Mathematical Structures in Computer Science. 29:927-937
This article continues the study of the definability in the local substructure $\mathcal{G}_{T,\omega}$ of the ω-Turing degrees, initiated in (Sariev and Ganchev 2014). We show that the class I of the intermediate degrees is definable in $\mathcal{G
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::e196db96b314da81f6a188283d437bb9
https://doi.org/10.1017/s0960129519000021
https://doi.org/10.1017/s0960129519000021
Autor:
Mariya Ivanova Soskova, Hristo Ganchev
Publikováno v:
Computability. 7:179-188
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::2df9cbc955d944a7a4fc05565a3474ed
https://doi.org/10.3233/com-170072
https://doi.org/10.3233/com-170072
Publikováno v:
Computing with Foresight and Industry ISBN: 9783030229955
CiE
CiE
We study computable embeddings for pairs of structures, i.e. for classes containing precisely two non-isomorphic structures. We show that computable embeddings induce a non-trivial degree structure for two-element classes consisting of computable str
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::824f6d536c4e6816427475ffa71192a7
https://doi.org/10.1007/978-3-030-22996-2_8
https://doi.org/10.1007/978-3-030-22996-2_8
Autor:
Hristo Ganchev, Andrea Sorbi
Publikováno v:
The Journal of Symbolic Logic. 81:316-325
Using properties of${\cal K}$-pairs of sets, we show that every nonzero enumeration degreeabounds a nontrivial initial segment of enumeration degrees whose nonzero elements have all the same jump asa. Some consequences of this fact are derived, that
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::f5f66964ff784d3c73ed0214146ab654
https://doi.org/10.1017/jsl.2014.84
https://doi.org/10.1017/jsl.2014.84
Autor:
Hristo Ganchev, Mariya Ivanova Soskova
Publikováno v:
Transactions of the American Mathematical Society. 367:4873-4893
We give an alternative definition of the enumeration jump operator. We prove that the class of total enumeration degrees and the class of low enumeration degrees are first order definable in the local substructure of the enumeration degree, consistin
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::d490788b7922177ad31851709075978a
https://doi.org/10.1090/s0002-9947-2014-06157-6
https://doi.org/10.1090/s0002-9947-2014-06157-6
Autor:
Hristo Ganchev, Andrey C. Sariev
Publikováno v:
Annals of Pure and Applied Logic. 165:1512-1532
In this paper we initiate the study of the ω -Turing reducibility between sequences of sets of natural numbers. We shall prove that the induced degree structure is an extension of the structure of the Turing degrees and that the two structures are c
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::962b02d51c80dfe1331df735d2b33e73
https://doi.org/10.1016/j.apal.2014.04.017
https://doi.org/10.1016/j.apal.2014.04.017
We show that every nonzero $${\Delta^{0}_{2}}$$Δ20 enumeration degree bounds the enumeration degree of a 1-generic set. We also point out that the enumeration degrees of 1-generic sets, below the first jump, are not downwards closed, thus answering
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::3df9165c2db00acea0eab46a8b1aba0b
http://hdl.handle.net/11365/990172
http://hdl.handle.net/11365/990172