Title :
Hyper-polynomial hierarchies and the NP-jump
Author :
Fenner, Stephen ; Homer, Steven ; Pruim, Randall ; Schaefer, Marcus
Author_Institution :
Dept. of Comput. Sci., Univ. of Southern Maine, Portland, ME, USA
Abstract :
Assuming that the polynomial hierarchy (PH) does not collapse, we show the existence of ascending sequences of ptime Turing degrees of length ω1CK all of which are in PSPACE and uniformly hard for PH, such that successors are NP-jumps of their predecessors. This is analogous to the hyperarithmetic hierarchy which is defined similarly but with the (recursive) Turing degrees. The lack of uniform least upper bounds for ascending sequences of ptime degrees causes (the limit levels of) our hyper-polynomial hierarchy to be inherently non-canonical. This problem is investigated in depth, and various possible structures for hyper-polynomial hierarchies are explicated, as are properties of the NP-jump operator on the languages which are in PSPACE but not in PH
Keywords :
Turing machines; computational complexity; NP-jump; PSPACE; ascending sequences; hyper-polynomial hierarchies; ptime Turing degrees; uniform least upper bounds; Arithmetic; Complexity theory; Computer science; Educational institutions; Logic; Polynomials; Upper bound;
Conference_Titel :
Computational Complexity, 1997. Proceedings., Twelfth Annual IEEE Conference on (Formerly: Structure in Complexity Theory Conference)
Conference_Location :
Ulm
Print_ISBN :
0-8186-7907-7
DOI :
10.1109/CCC.1997.612305