Abstract
This paper considers reductions between types of numberings; these reductions preserve the Rogers Semilattice of the numberings reduced and also preserve the number of minimal and positive degrees in their semilattice. It is shown how to use these reductions to simplify some constructions of specific semilattices. Furthermore, it is shown that for the basic types of numberings, one can reduce the left-r.e. numberings to the r.e. numberings and the k-r.e. numberings to the (k+1)-r.e. numberings; all further reductions are obtained by concatenating these reductions.
| Original language | English |
|---|---|
| Article number | 102716 |
| Pages (from-to) | 1-30 |
| Number of pages | 30 |
| Journal | Annals of Pure and Applied Logic |
| Volume | 170 |
| Issue number | 12 |
| DOIs | |
| Publication status | Published - Dec 2019 |
Keywords
- Ordinals in recursion theory
- Recursively enumerable sets
- Reducibilities between numberings
- Theory of numberings in the difference hierarchy
- n-r.e. sets
ASJC Scopus subject areas
- Logic
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