Randomness notions and partial relativization
نویسندگان
چکیده
منابع مشابه
Randomness notions and partial relativization
We study weak 2 randomness, weak randomness relative to ∅′ and Schnorr randomness relative to ∅′. One major theme is characterizing the oracles A such that ML[A] ⊆ C, where C is a randomness notion and ML[A] denotes the Martin-Löf random reals relative to A. We discuss the connections with LR-reducibility and also study the reducibility associated with weak 2randomness.
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We compare various notions of algorithmic randomness. First we consider relativized randomness. A set is ?-random if it is Martin-L?f random relative to 0_1). We show that a set is 2-random if and only if there is a constant c such that infinitely many initial segments x of the set are c-incompressible: C(x) > |x| ? c. The 'only if direction was obtained independently by Joseph Miller. This cha...
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It is an open problem in the area of computable randomness whether Kolmogorov-Loveland randomness coincides with Martin-Löf randomness. Joe Miller and André Nies suggested some variations of Kolmogorov-Loveland randomness to approach this problem and to provide a partial solution. We show that their proposed notion of partial permutation randomness is still weaker than Martin-Löf randomness.
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Schnorr famously proved that Martin-Löf-randomness of a sequence A can be characterised via the complexity of A’s initial segments. Nies, Stephan and Terwijn as well as independently Miller showed that Kolmogorov randomness coincides with Martin-Löf randomness relative to the halting problem K; that is, a set A is Martin-Löf random relative to K iff there is no function f such that for all m an...
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We study randomness notions given by higher recursion theory, establishing the relationships Π1-randomness ⊂ Π1-Martin-Löf randomness ⊂ ∆1randomness = ∆1-Martin-Löf randomness. We characterize the set of reals that are low for ∆1 randomness as precisely those that are ∆ 1 1 -traceable. We prove that there is a perfect set of such reals.
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ژورنال
عنوان ژورنال: Israel Journal of Mathematics
سال: 2012
ISSN: 0021-2172,1565-8511
DOI: 10.1007/s11856-012-0012-5