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Author: Publisher: ISBN: Category : Languages : en Pages : 93
Book Description
Algorithmic randomness uses tools from computability theory to give precise formulations for what it means for mathematical objects to be random. When the objects in question are reals (infinite sequences of zeros and ones), it reveals complex interactions between how random they are and how useful they are as computational oracles. The results in this thesis are primarily on interactions of this nature. Chapter 1 provides a brief introduction to notation and basic notions from computability theory. Chapter 2 is on shift-complex sequences, also known as everywhere complex sequences. These are sequences all of whose substrings have uniformly high prefix-free Kolmogorov complexity. Rumyantsev showed that the measure of oracles that compute shift-complex sequences is 0. We refine this result to show that the Martin-Löf random sequences that compute shift-complex sequences compute the halting problem. In the other direction, we answer the question of whether every Martin-Löf random sequence computes a shift-complex sequence in the negative by translating it into a question about diagonally noncomputable (or DNC) functions. The key in this result is analyzing how growth rates of DNC functions affect what they can compute. This is the subject of Chapter 3. Using bushy-tree forcing, we show (with J. Miller) that there are arbitrarily slow-growing (but unbounded) DNC functions that fail to compute a Kurtz random sequence. We also extend Kumabe's result that there is a DNC function of minimal Turing degree by showing that for every oracle X, there is a function f that is DNC relative to X and of minimal Turing degree. Chapter 4 is on how "effective" Lebesgue density interacts with computability-theoretic strength and randomness. Bienvenu, Hölzl, Miller, and Nies showed that if we restrict our attention to the Martin-Löf random sequences, then the positive density sequences are exactly the ones that do not compute the halting problem. We prove several facts around this theorem. For example, one direction of the theorem fails without the assumption of Martin-Löf randomness: Given any sequence X, there is a density-one sequence Y that computes it. Another question we answer is whether a positive density point can have minimal degree. It turns out that every such point is either Martin-Löf random, or computes a 1-generic. In either case, it is nonminimal.
Author: Publisher: ISBN: Category : Languages : en Pages : 93
Book Description
Algorithmic randomness uses tools from computability theory to give precise formulations for what it means for mathematical objects to be random. When the objects in question are reals (infinite sequences of zeros and ones), it reveals complex interactions between how random they are and how useful they are as computational oracles. The results in this thesis are primarily on interactions of this nature. Chapter 1 provides a brief introduction to notation and basic notions from computability theory. Chapter 2 is on shift-complex sequences, also known as everywhere complex sequences. These are sequences all of whose substrings have uniformly high prefix-free Kolmogorov complexity. Rumyantsev showed that the measure of oracles that compute shift-complex sequences is 0. We refine this result to show that the Martin-Löf random sequences that compute shift-complex sequences compute the halting problem. In the other direction, we answer the question of whether every Martin-Löf random sequence computes a shift-complex sequence in the negative by translating it into a question about diagonally noncomputable (or DNC) functions. The key in this result is analyzing how growth rates of DNC functions affect what they can compute. This is the subject of Chapter 3. Using bushy-tree forcing, we show (with J. Miller) that there are arbitrarily slow-growing (but unbounded) DNC functions that fail to compute a Kurtz random sequence. We also extend Kumabe's result that there is a DNC function of minimal Turing degree by showing that for every oracle X, there is a function f that is DNC relative to X and of minimal Turing degree. Chapter 4 is on how "effective" Lebesgue density interacts with computability-theoretic strength and randomness. Bienvenu, Hölzl, Miller, and Nies showed that if we restrict our attention to the Martin-Löf random sequences, then the positive density sequences are exactly the ones that do not compute the halting problem. We prove several facts around this theorem. For example, one direction of the theorem fails without the assumption of Martin-Löf randomness: Given any sequence X, there is a density-one sequence Y that computes it. Another question we answer is whether a positive density point can have minimal degree. It turns out that every such point is either Martin-Löf random, or computes a 1-generic. In either case, it is nonminimal.
Author: Hector Zenil Publisher: World Scientific ISBN: 9814327743 Category : Computers Languages : en Pages : 439
Book Description
This review volume consists of an indispensable set of chapters written by leading scholars, scientists and researchers in the field of Randomness, including related subfields specially but not limited to the strong developed connections to the Computability and Recursion Theory. Highly respected, indeed renowned in their areas of specialization, many of these contributors are the founders of their fields. The scope of Randomness Through Computation is novel. Each contributor shares his personal views and anecdotes on the various reasons and motivations which led him to the study of the subject. They share their visions from their vantage and distinctive viewpoints. In summary, this is an opportunity to learn about the topic and its various angles from the leading thinkers.
Author: Rodney G. Downey Publisher: Springer Science & Business Media ISBN: 0387684417 Category : Computers Languages : en Pages : 883
Book Description
Computability and complexity theory are two central areas of research in theoretical computer science. This book provides a systematic, technical development of "algorithmic randomness" and complexity for scientists from diverse fields.
Author: Johanna N. Y. Franklin Publisher: Cambridge University Press ISBN: 1108808271 Category : Mathematics Languages : en Pages : 371
Book Description
The last two decades have seen a wave of exciting new developments in the theory of algorithmic randomness and its applications to other areas of mathematics. This volume surveys much of the recent work that has not been included in published volumes until now. It contains a range of articles on algorithmic randomness and its interactions with closely related topics such as computability theory and computational complexity, as well as wider applications in areas of mathematics including analysis, probability, and ergodic theory. In addition to being an indispensable reference for researchers in algorithmic randomness, the unified view of the theory presented here makes this an excellent entry point for graduate students and other newcomers to the field.
Author: Noam Greenberg Publisher: World Scientific ISBN: 9811278644 Category : Mathematics Languages : en Pages : 492
Book Description
This volume results from two programs that took place at the Institute for Mathematical Sciences at the National University of Singapore: Aspects of Computation — in Celebration of the Research Work of Professor Rod Downey (21 August to 15 September 2017) and Automata Theory and Applications: Games, Learning and Structures (20-24 September 2021).The first program was dedicated to the research work of Rodney G. Downey, in celebration of his 60th birthday. The second program covered automata theory whereby researchers investigate the other end of computation, namely the computation with finite automata, and the intermediate level of languages in the Chomsky hierarchy (like context-free and context-sensitive languages).This volume contains 17 contributions reflecting the current state-of-art in the fields of the two programs.
Author: Adam Day Publisher: Springer ISBN: 3319500627 Category : Computers Languages : en Pages : 788
Book Description
This Festschrift is published in honor of Rodney G. Downey, eminent logician and computer scientist, surfer and Scottish country dancer, on the occasion of his 60th birthday. The Festschrift contains papers and laudations that showcase the broad and important scientific, leadership and mentoring contributions made by Rod during his distinguished career. The volume contains 42 papers presenting original unpublished research, or expository and survey results in Turing degrees, computably enumerable sets, computable algebra, computable model theory, algorithmic randomness, reverse mathematics, and parameterized complexity, all areas in which Rod Downey has had significant interests and influence. The volume contains several surveys that make the various areas accessible to non-specialists while also including some proofs that illustrate the flavor of the fields.
Author: Florin Manea Publisher: Springer ISBN: 3319944185 Category : Computers Languages : en Pages : 448
Book Description
This book constitutes the refereed proceedings of the 14th Conference on Computability in Europe, CiE 2018, held in Kiel, Germany, in July/ August 2017. The 26 revised full papers were carefully reviewed and selected from 55 submissions. In addition, this volume includes 15 invited papers. The conference CiE 2018 has six special sessions, namely: Approximation and optimization, Bioinformatics and bio-inspired computing, computing with imperfect information, continuous computation, history and philosophy of computing (celebrating the 80th birthday of Martin Davis), and SAT-solving.
Author: Ming Yang Li Publisher: ISBN: Category : Languages : en Pages :
Book Description
Algorithmic randomness is the study of random objects through computability theoretic means. In this dissertation, we study the concept of randomness with respect to continuous measures in two different approaches, measure theoretical randomness tests and algorithmic information complexity. Our main focus is the set NCR of infinite binary sequences that are not random with respect to any continuous measure. To this end, we first introduce a new, parameterized randomness test with respect to a continuous measure (Chapter 2). The main feature of the new test is that it applies and iterates the dissipation function of a measure. We prove our new test satisfies properties common for other, well-studied notions of randomness tests.We also show that, even though our test is strictly stronger than Martin-L\"{o}f tests for some individual measures, they coincide with Martin-L\"{o}f randomness when considering all continuous measures simultaneously ( Chapter 2 and Chapter 4). Next, we apply the new test notion to construct some new, previously unknown examples of NCR reals (Chapter 3). We constructively show that every Turing degree recursively enumerable above an NCR real contains an NCR real. We also construct an NCR real in every self-modulus degree. A direct corollary from either construction is that NCR reals exists in every $\Delta^0_2$ degree. Moreover, we also show that our constructive methods are versatile, by constructing examples like 1-generic NCR reals or NCR reals of effective packing dimension 1. We also construct a pair of never simultaneously continuously random reals neither of which is NCR. This answers a question by Adam Day and Andrew Marks. We then move on to investigating the complexity notion of NCR reals (Chapter 4). By using prefix-free complexity and a priori complexity as tools, we are able to show that NCR in Martin-L\"{o}f's sense and NCR in the sense of our new test notion have the same algorithmic complexity description and thus coincide. Finally, we study the descriptive complexity of NCR reals (Chapter 5). We prove that never random with respect to a $\Pi^0_1$ class of measures is arithmetically definable. As an application of our result, we show that the set of $\Delta^0_2$ NCR reals is arithmetic.
Author: André Nies Publisher: OUP Oxford ISBN: 0191627887 Category : Mathematics Languages : en Pages : 450
Book Description
The interplay between computability and randomness has been an active area of research in recent years, reflected by ample funding in the USA, numerous workshops, and publications on the subject. The complexity and the randomness aspect of a set of natural numbers are closely related. Traditionally, computability theory is concerned with the complexity aspect. However, computability theoretic tools can also be used to introduce mathematical counterparts for the intuitive notion of randomness of a set. Recent research shows that, conversely, concepts and methods originating from randomness enrich computability theory. The book covers topics such as lowness and highness properties, Kolmogorov complexity, betting strategies and higher computability. Both the basics and recent research results are desribed, providing 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.
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Author: 
Author: Hector Zenil
Author: Rodney G. Downey
Author: Johanna N. Y. Franklin
Author: Noam Greenberg
Author: Adam Day
Author: Florin Manea
Author: Ming Yang Li
Author: André Nies
Author: Michael Patrick McInerney