#### Filter Results:

#### Publication Year

2006

2016

#### Co-author

#### Key Phrase

#### Publication Venue

Learn More

For any enumeration degree a let D s a be the set of s-degrees contained in a. We answer an open question of Watson by showing that if a is a nontrivial Σ 0 2-enumeration degree, then D s a has no least element. We also show that every countable partial order embeds into D s a .

For any enumeration degree a let D s a be the set of s-degrees contained in a. We answer an open question of Watson by showing that if a is a nontrivial Σ 0 2-enumeration degree, then D s a has no least element. We also show that every countable partial order embeds into D s a. Finally, we construct Σ 0 2-sets A and B such that B ≤ e A but for every X ≡ e… (More)

- ‹
- 1
- ›