Muutke küpsiste eelistusi

Computability and Randomness [Kõva köide]

(, Senior Lecturer, Department of Computer Science, The University of Aukland)
  • Formaat: Hardback, 450 pages, kõrgus x laius x paksus: 239x162x27 mm, kaal: 811 g, 13 line illustrations
  • Sari: Oxford Logic Guides 51
  • Ilmumisaeg: 29-Jan-2009
  • Kirjastus: Oxford University Press
  • ISBN-10: 0199230765
  • ISBN-13: 9780199230761
  • Formaat: Hardback, 450 pages, kõrgus x laius x paksus: 239x162x27 mm, kaal: 811 g, 13 line illustrations
  • Sari: Oxford Logic Guides 51
  • Ilmumisaeg: 29-Jan-2009
  • Kirjastus: Oxford University Press
  • ISBN-10: 0199230765
  • ISBN-13: 9780199230761
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.

Covering the basics as well as recent research results, this book provides 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.
The complexity of sets
1(73)
The basic concepts
3(5)
Partial computable functions
3(3)
Computably enumerable sets
6(1)
Indices and approximations
7(1)
Relative computational complexity of sets
8(8)
Many-one reducibility
8(1)
Turing reducibility
9(1)
Relativization and the jump operator
10(2)
Strings over {0,1}
12(1)
Approximating the functionals φe, and the use principle
13(1)
Weak truth-table reducibility and truth-table reducibility
14(2)
Degree structures
16(1)
Sets of natural numbers
16(2)
Descriptive complexity of sets
18(6)
Δ02 sets and the Shoenfield Limit Lemma
18(1)
Sets and functions that are n-c.e. or w-c.e.
19(1)
Degree structures on particular classes
20(1)
The arithmetical hierarchy
21(3)
Absolute computational complexity of sets
24(5)
Sets that are lown
26(1)
Computably dominated sets
27(1)
Sets that are highn
28(1)
Post's problem
29(8)
Turing incomparable Δ02-sets
30(1)
Simple sets
31(1)
A c.e. set that is neither computable nor Turing complete
32(2)
Is there a natural solution to Post's problem?
34(1)
Turing incomparable c.e. sets
35(2)
Properties of c.e. sets
37(8)
Each incomputable c.e. wtt-degree contains a simple set
38(1)
Hypersimple sets
39(1)
Promptly simple sets
40(1)
Minimal pairs and promptly simple sets
41(2)
Creative sets
43(2)
Cantor space
45(23)
Open sets
47(1)
Binary trees and closed sets
47(1)
Representing open sets
48(1)
Compactness and clopen sets
48(1)
The correspondence between subsets of N and real numbers
49(1)
Effectivity notions for real numbers
50(2)
Effectivity notions for classes of sets
52(3)
Examples of II01 classes
55(1)
Isolated points and perfect sets
56(1)
The Low Basis Theorem
56(3)
The basis theorem for computably dominated sets
59(2)
Weakly 1-generic sets
61(2)
1-generic sets
63(1)
The arithmetical hierarchy of classes
64(3)
Comparing Cantor space with Baire space
67(1)
Measure and probability
68(6)
Outer measures
68(1)
Measures
69(1)
Uniform measure and null classes
70(1)
Uniform measure of arithmetical classes
71(2)
Probability theory
73(1)
The descriptive complexity of strings
74(28)
Comparing the growth rate of functions
75(1)
The plain descriptive complexity C
75(7)
Machines and descriptions
75(2)
The counting condition, and incompressible strings
77(2)
Invariance, continuity, and growth of C
79(2)
Algorithmic properties of C
81(1)
The prefix-free complexity K
82(10)
Drawbacks of C
83(1)
Prefix-free machines
83(3)
The Machine Existence Theorem and a characterization of K
86(5)
The Coding Theorem
91(1)
Conditional descriptive complexity
92(2)
Basics
92(1)
An expression for K (x, y)
93(1)
Relating C and K
94(3)
Basic interactions
94(1)
Solovay's equations
95(2)
Incompressibility and randomness for strings
97(5)
Comparing incompressibility notions
98(1)
Randomness properties of strings
99(3)
Martin-Lof randomness and its variants
102(42)
A mathematical definition of randomness for sets
102(4)
Martin-Lof tests and their variants
104(1)
Schnorr's Theorem and universal Martin-Lof tests
105(1)
The initial segment approach
105(1)
Martin-Lof randomness
106(11)
The test concept
106(1)
A universal Martin-Lof test
107(1)
Characterization of MLR via the initial segment complexity
107(1)
Examples of Martin-Lof random sets
108(1)
Facts about ML-random sets
109(4)
Left-c.e. ML-random reals and Solovay reducibility
113(2)
Randomness on reals, and randomness for bases other than 2
115(1)
A nonempty II01 subclass of MLR has ML-random measure
116(1)
Martin-Lof randomness and reduction procedures
117(3)
Each set is weak truth-table reducible to a ML-random set
117(2)
Autoreducibility and indifferent sets
119(1)
Martin-Lof randomness relative to an oracle
120(7)
Relativizing C and K
121(1)
Basics of relative ML-randomness
122(1)
Symmetry of relative Martin-Lof randomness
122(2)
Computational complexity, and relative randomness
124(1)
The halting probability Ω relative to an oracle
125(2)
Notions weaker than ML-randomness
127(6)
Weak randomness
128(1)
Schnorr randomness
129(2)
Computable measure machines
131(2)
Notions stronger than ML-randomness
133(11)
Weak 2-randomness
134(2)
2-randomness and initial segment complexity
136(4)
2-randomness and being low for Ω
140(1)
Demuth randomness
141(3)
Diagonally noncomputable functions
144(19)
D.n.c. functions and sets of d.n.c. degree
145(5)
Basics on d.n.c. functions and fixed point freeness
145(2)
The initial segment complexity of sets of d.n.c. degree
147(1)
A completeness criterion for c.e. sets
148(2)
Injury-free constructions of c.e. sets
150(5)
Each Δ02 set of d.n.c. degree bounds a promptly simple set
151(1)
Variants of Kucera's Theorem
152(2)
An injury-free proof of the Friedberg-Muchnik Theorem
154(1)
Strengthening the notion of a d.n.c. function
155(8)
Sets of PA degree
156(1)
Martin-Lof random sets of PA degree
157(2)
Turing degrees of Martin-Lof random sets
159(1)
Relating n-randomness and higher fixed point freeness
160(3)
Lowness properties and K-triviality
163(75)
Equivalent lowness properties
165(11)
Being low for K
165(2)
Lowness for ML-randomness
167(1)
When many oracles compute a set
168(2)
Bases for ML-randomness
170(4)
Lowness for weak 2-randomness
174(2)
K-trivial sets
176(8)
Basics on K-trivial sets
176(1)
K-trivial sets are Δ
177(2)
The number of sets that are K-trivial for a constant b
179(2)
Closure properties of K
181(1)
C-trivial sets
182(1)
Replacing the constant by a slowly growing function
183(1)
The cost function method
184(16)
The basics of cost functions
186(2)
A cost function criterion for K-triviality
188(1)
Cost functions and injury-free solutions to Post's problem
189(1)
Construction of a promptly simple Turing lower bound
190(2)
K-trivial sets and σ-induction
192(1)
A voiding to be Turing reducible to a given low c.e. set
193(2)
Necessity of the cost function method for c.e. K-trivial sets
195(1)
Listing the (w-c.e.) K-trivial sets with constants
196(2)
Adaptive cost functions
198(2)
Each K-trivial set is low for K
200(15)
Introduction to the proof
201(9)
The formal proof of Theorem 5.4.1
210(5)
Properties of the class of K-trivial sets
215(9)
A Main Lemma derived from the golden run method
215(2)
The standard cost function characterizes the K-trivial sets
217(2)
The number of changes
219(2)
δA for K-trivial A
221(2)
Each K-trivial set is low for weak 2-randomness
223(1)
The weak reducibility associated with Low(MLR)
224(14)
Preorderings coinciding with LR-reducibility
226(2)
A stronger result under the extra hypothesis that A ≤t B'
228(2)
The size of lower and upper cones for ≤lr
230(1)
Operators obtained by relativizing classes
231(1)
Studying ≤lr by applying the operator K
232(1)
Comparing the operators Slr and K
233(1)
Uniformly almost everywhere dominating sets
234(1)
^≤LR C if and only if C is uniformly a.e. dominating
235(3)
Some advanced computability theory
238(21)
Enumerating Turing functionals
239(3)
Basics and a first example
239(1)
C.e. oracles, markers, and a further example
240(2)
Promptly simple degrees and low cuppability
242(5)
C.e. sets of promptly simple degree
243(1)
A c.e. degree is promptly simple iff it is low cuppable
244(3)
C.e. operators and highness properties
247(12)
The basics of c.e. operators
247(2)
Pseudojump inversion
249(2)
Applications of pseudojump inversion
251(2)
Inversion of a c.e. operator via a ML-random set
253(3)
Separation of highness properties
256(2)
Minimal pairs and highness properties
258(1)
Randomness and betting strategies
259(42)
Martingales
260(4)
Formalizing the concept of a betting strategy
260(1)
Supermartingales
261(1)
Some basics on supermartingales
262(1)
Sets on which a supermartingale fails
263(1)
Characterizing null classes by martingales
264(1)
C.e. supermartingales and ML-randomness
264(4)
Computably enumerable supermartingales
265(1)
Characterizing ML-randomness via c.e. supermartingales
265(1)
Universal c.e. supermartingales
266(1)
The degree of nonrandomness in ML-random sets
266(2)
Computable supermartingales
268(3)
Schnorr randomness and martingales
268(2)
Preliminaries on computable martingales
270(1)
How to build a computably random set
271(8)
Three preliminary Theorems: outline
272(1)
Partial computable martingales
273(1)
A template for building a computably random set
274(1)
Computably random sets and initial segment complexity
275(2)
The case of a partial computably random set
277(2)
Each high degree contains a computably random set
279(9)
Martingales that dominate
279(1)
Each high c.e. degree contains a computably random left-c.e. set
280(1)
A computably random set that is not partial computably random
281(2)
A strictly computably random set in each high degree
283(2)
A strictly Schnorr random set in each high degree
285(3)
Varying the concept of a betting strategy
288(13)
Basics of selection rules
288(1)
Stochasticity
288(1)
Stochasticity and initial segment complexity
289(5)
Nonmonotonic betting strategies
294(1)
Muchnik's splitting technique
295(2)
Kolmogorov-Loveland randomness
297(4)
Classes of computational complexity
301(64)
The class Low(δ)
303(9)
The Low(δ) basis theorem
303(2)
Being weakly low for K
305(3)
2-randomness and strong incompressibility k
308(1)
Each computably dominated set in Low(δ) is computable
309(2)
A related result on computably dominated sets in GL1
311(1)
Traceability
312(9)
C.e. traceable sets and array computable sets
313(3)
Computably traceable sets
316(2)
Lowness for computable measure machines
318(1)
Facile sets as an analog of the K-trivial sets
319(2)
Lowness for randomness notions
321(15)
Lowness for C-null classes
322(1)
The class Low(MLR, SR)
323(3)
Classes that coincide with Low(SR)
326(2)
Low(MLR, CR) coincides with being low for K
328(8)
Jump traceability
336(12)
Basics of jump traceability, and existence theorems
336(2)
Jump traceability and descriptive string complexity
338(1)
The weak reducibility associated with jump traceability
339(2)
Jump traceability and superlowness are equivalent for c.e. sets
341(2)
More on weak reducibilities
343(1)
Strong jump traceability
343(3)
Strong superlowness
346(2)
Subclasses of the K-trivial sets
348(13)
Some K-trivial c.e. set is not strongly jump traceable
348(3)
Strongly jump traceable c.e. sets and benign cost functions
351(5)
The diamond operator
356(5)
Summary and discussion
361(4)
A diagram of downward closed properties
361(2)
Computational complexity versus randomness
363(1)
Some updates
364(1)
Higher computability and randomness
365(20)
Preliminaries on higher computability theory
366(6)
II11 and other relations
366(1)
Well-orders and computable ordinals
367(1)
Representing II11 relations by well-orders
367(2)
II11 classes and the uniform measure
369(1)
Reducibilities
370(1)
A set theoretical view
371(1)
Analogs of Martin-Lof randomness and K-triviality
372(6)
II11 Machines and prefix-free complexity
373(3)
A version of Martin-Lof randomness based on II sets
376(1)
An analog of K-triviality
376(1)
Lowness for II-ML-randomness
377(1)
Δ11-randomness and II-randomness
378(3)
Notions that coincide with δ-randomness
379(1)
More on II-randomness
380(1)
Lowness properties in higher computability theory
381(4)
Hyp-dominated sets
381(1)
Traceability
382(3)
Solutions to the exercises
385(25)
Solutions to
Chapter 1
385(4)
Solutions to
Chapter 2
389(2)
Solutions to
Chapter 3
391(2)
Solutions to
Chapter 4
393(2)
Solutions to
Chapter 5
395(4)
Solutions to
Chapter 6
399(1)
Solutions to
Chapter 7
400(2)
Solutions to
Chapter 8
402(6)
Solutions to
Chapter 9
408(2)
References 410(8)
Notation Index 418(5)
Index 423
André Nies received his PhD in Mathematics form the University of Heidelberg, Germany, in 1992. From 1994 to 1995 he was a Visiting Professor at the University of Wisconsin at Madison and Cornell. In 1995 he took the post of Assistant Professor at the University of Chicago. Since 2002 he has been Senior Lecturer in the Department of Computer Science, University of Aukland.