The Turing Hierarchy of Unsolvability

Autor: Borut Robič
Rok vydání: 2020
Předmět:
Zdroj: The Foundations of Computability Theory ISBN: 9783662624203
The Foundations of Computability Theory ISBN: 9783662448076
DOI: 10.1007/978-3-662-62421-0_12
Popis: At this point we only know of two degrees of unsolvability: the T-degree shared by all the decidable decision problems, and the T-degree shared by all undecidable decision problems that are T-equivalent to the Halting Problem. In this chapter we will prove that, surprisingly, for every undecidable decision problem there exists a more difficult decision problem. This will in effect mean that there is an infinite hierarchy of degrees of unsolvability and that there is no most difficult decision problem.
Databáze: OpenAIRE