Computability in Europe 2008
Logic and Theory of Algorithms

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Regular Talk:
Upper Semilattices in Many-One Degrees

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Speaker: Sergei Podzorov
Slot: Thu, 11:00-11:20, Room 24 (col. 3)

Abstract

The paper gives an overview over recent results of the author on various
upper semilattices of many-one degrees. The local
isomorphism type (i.e. the collection of isomorphism types of all
principal ideals) of $m$-degrees belonging to any fixed class of
arithmetical hierarchy is completely described. The description of
the semilattices of simple, hypersimple and $\Delta^0_2$ $m$-degrees up to
isomorphism is also given.

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