Elementary differences among jump classes

It is shown that Th ( H 1 ) ≠ Th ( H n ) holds for every n > 1, where H m is the upper semi-lattice of all high m computably enumerable (c. e.) degrees for m > 0, giving a first elementary difference among the highness hierarchies of the c. e. degrees.

Authors

• Angsheng Li Beihang University Zhongguancun Laboratory, Beijing, China

Keywords

• Computably enumerable sets
• Turing degrees
• Turing jump