Logical Approaches to Computational Barriers

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 |