Computability in Europe 2006
Logical Approaches to Computational Barriers

Regular Talk:
Upper Semilattices in Many-One Degrees

Speaker: Sergei Podzorov
Slot: Array, 11:00-11:20, col. 3


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.

websites: Arnold Beckmann 2008-05-18