About Not Countable Ideals in a Semi-Lattice of the Enumeration Degrees
نویسندگان
چکیده
منابع مشابه
Embedding countable partial orderings in the enumeration degrees and the ω-enumeration degrees
One 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 results: Mostowski [15] proves that there is a computable partial ordering in which every countable partial ordering can be embedded. Kleene and Post [10...
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We show that the 0 2 enumeration degrees are not dense. This answers a question posed by Cooper. 1 Background Cooper 3] showed that the enumeration degrees (e-degrees) are not dense. He also showed that the e-degrees of the 0 2 sets are dense 2]. Since Cooper's nondensity proof constructs a 0 7 set, he posed the question: What is the least n (2 n 6) such that the e-degrees below 0 n are not den...
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we show that the lattice of all ideals of a ring $r$ can be embedded in the lattice of all its fuzzyideals in uncountably many ways. for this purpose, we introduce the concept of the generalizedcharacteristic function $chi _{s}^{r} (a)$ of a subset $a$ of a ring $r$ forfixed $r , sin [0,1] $ and show that $a$ is an ideal of $r$ if, and only if, its generalizedcharacteristic function $chi _{s}^{...
متن کاملDefinability in the enumeration degrees
We prove that every countable relation on the enumeration degrees, E, is uniformly definable from parameters in E. Consequently, the first order theory of E is recursively isomorphic to the second order theory of arithmetic. By an effective version of coding lemma, we show that the first order theory of the enumeration degrees of the Σ2 sets is not decidable.
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ژورنال
عنوان ژورنال: Modeling and Analysis of Information Systems
سال: 2015
ISSN: 2313-5417,1818-1015
DOI: 10.18255/1818-1015-2012-5-74-80