scispace - formally typeset
Open AccessJournal ArticleDOI

Two recursively enumerable sets of incomparable degrees of unsolvability (solution of post's problem, 1944).

Richard Friedberg
- 15 Feb 1957 - 
- Vol. 43, Iss: 2, pp 236-238
Reads0
Chats0
About
This article is published in Proceedings of the National Academy of Sciences of the United States of America.The article was published on 1957-02-15 and is currently open access. It has received 259 citations till now. The article focuses on the topics: Recursively enumerable language.

read more

Citations
More filters
Journal ArticleDOI

Recursively enumerable sets and degrees

TL;DR: In this paper, the relation of the structure of an R set to its degree is discussed, and the infinite injury priority method is proposed to solve the problem of scaling and splitting R sets.
Book

Computability and randomness

André Nies
TL;DR: This book provides a very readable introduction to the exciting interface of computability and randomness for graduates and researchers in computability theory, theoretical computer science, and measure theory.
Journal ArticleDOI

Ramsey's Theorem and Recursion Theory

TL;DR: It is shown that if P is such a recursive partition of [ N ] n, then H ( P ) contains a set which is Π n 0 in the arithmetical hierarchy, and it is proved that for each n ≥ 2 there is a recursive partitions P of [N ] n into two classes such that H (P ) contains no Σ n 0 set.
Journal ArticleDOI

Lower Bounds for Pairs of Recursively Enumerable Degrees

TL;DR: In this paper, it was shown that the upper semi-lattice of the r.i.d. degrees is not a lattice, thus verifying another conjecture of Sacks ((4) 170): there exist two r.e.d degrees a, b whose greatest lower bound is 0.