Recursively enumerable sets and degrees
Recursively enumerable sets and degrees
Extension of embeddings on the recursively enumerable degrees modulo the cappable degrees
Computability, enumerability, unsolvability
Computability, enumerability, unsolvability
On the quotient structure of computably enumerable degrees modulo the noncuppable ideal
TAMC'06 Proceedings of the Third international conference on Theory and Applications of Models of Computation
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In this paper, we prove the existence of a minimal pair of c.e.degrees a and b such that both of them are cuppable, and noincomplete c.e. degree can cup both of them to 0'. As aconsequence, [a] and [b] form a minimal pair inM/NCup, the quotient structure of the cappabledegrees modulo noncuppable degrees. We also prove that the dual ofLempp's conjecture is true.