,
Fabian Egidy
,
Christian Glaßer
Creative Commons Attribution 4.0 International license
We construct an oracle relative to which NP = PSPACE, but UP has no many-one complete sets. This combines the properties of an oracle by Hartmanis and Hemachandra [J. Hartmanis and L. A. Hemachandra, 1988] and one by Ogiwara and Hemachandra [Ogiwara and Hemachandra, 1991]. The oracle provides new separations of classical conjectures on optimal proof systems and complete sets in promise classes. This answers several questions by Pudlák [P. Pudlák, 2017], e.g., the implications UP ⟹ CON^𝖭 and SAT ⟹ TFNP are false relative to our oracle. Moreover, the oracle demonstrates that, in principle, it is possible that TFNP-complete problems exist, while at the same time SAT has no p-optimal proof systems.
@InProceedings{dingel_et_al:LIPIcs.MFCS.2024.50,
author = {Dingel, David and Egidy, Fabian and Gla{\ss}er, Christian},
title = {{An Oracle with no UP-Complete Sets, but NP = PSPACE}},
booktitle = {49th International Symposium on Mathematical Foundations of Computer Science (MFCS 2024)},
pages = {50:1--50:17},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-335-5},
ISSN = {1868-8969},
year = {2024},
volume = {306},
editor = {Kr\'{a}lovi\v{c}, Rastislav and Ku\v{c}era, Anton{\'\i}n},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.MFCS.2024.50},
URN = {urn:nbn:de:0030-drops-206063},
doi = {10.4230/LIPIcs.MFCS.2024.50},
annote = {Keywords: Computational Complexity, Promise Classes, Complete Sets, Oracle Construction}
}