Add to ORKGOne of the most basic measures of the complexity of a given partially ordered structure is the quantity of partial orderings embeddable in this structure. In the structure of the Turing degrees, DT, this problem is investigated in a series of re-sults: Mostowski [15] proves that there is a computable partial ordering in whic
Abstract. A set A is symmetric enumeration (se-) reducible to a set B (A≤seB) if A is enumeration re...
Abstract. We investigate and extend the notion of a good approximation with respect to the enumerati...
Defining the degree of categoricity of a computable structure M to be the least degree d for which M...
We consider a measure Φ of computational complexity. The measure Φ determinesa binary relation on th...
We give a proof of the fact that in every nonempty interval of $\Sigma^0_2$ enumeration degrees one ...
Let P(A) be the following property, where A is any infinite set of natural numbers: (∀X)[X ⊆ A ∧ |A ...
Abstract. We give an algorithm for deciding whether an embedding of a finite partial order P into th...
Abstract. We show that if A and B form a nontrivial K-pair, then there is a semi-computable set C su...
This thesis is concerned with various degree structures below 0', varying from Turing degrees to tr...
The structure of the Turing degrees was introduced by Kleene and Post in 1954 [KP54]. Since then, it...
We establish that for every computably enumerable (c.e.) Turing degree b the upper cone of c.e. Turi...
Let $P(A)$ be the following property, where $A$ is any infinite set of natural numbers: \begin{displ...
We show that no nontrivial principal ideal of the enumeration degrees is linearly ordered: in fact, ...
Linear orders and initial segments A linear order may be highly computable, but have complicated ini...
In this paper we investigate questions about the definability of classes of n-computably enumerable ...
Abstract. A set A is symmetric enumeration (se-) reducible to a set B (A≤seB) if A is enumeration re...
Abstract. We investigate and extend the notion of a good approximation with respect to the enumerati...
Defining the degree of categoricity of a computable structure M to be the least degree d for which M...
We consider a measure Φ of computational complexity. The measure Φ determinesa binary relation on th...
We give a proof of the fact that in every nonempty interval of $\Sigma^0_2$ enumeration degrees one ...
Let P(A) be the following property, where A is any infinite set of natural numbers: (∀X)[X ⊆ A ∧ |A ...
Abstract. We give an algorithm for deciding whether an embedding of a finite partial order P into th...
Abstract. We show that if A and B form a nontrivial K-pair, then there is a semi-computable set C su...
This thesis is concerned with various degree structures below 0', varying from Turing degrees to tr...
The structure of the Turing degrees was introduced by Kleene and Post in 1954 [KP54]. Since then, it...
We establish that for every computably enumerable (c.e.) Turing degree b the upper cone of c.e. Turi...
Let $P(A)$ be the following property, where $A$ is any infinite set of natural numbers: \begin{displ...
We show that no nontrivial principal ideal of the enumeration degrees is linearly ordered: in fact, ...
Linear orders and initial segments A linear order may be highly computable, but have complicated ini...
In this paper we investigate questions about the definability of classes of n-computably enumerable ...
Abstract. A set A is symmetric enumeration (se-) reducible to a set B (A≤seB) if A is enumeration re...
Abstract. We investigate and extend the notion of a good approximation with respect to the enumerati...
Defining the degree of categoricity of a computable structure M to be the least degree d for which M...