Chapter
Basic notions and notation
Introduction. What is this book about?
What is Kolmogorov complexity?
Optimal description modes
Complexity and information
Complexity and randomness
Non-computability of \KS and Berry’s paradox
Some applications of Kolmogorov complexity
Chapter 1. Plain Kolmogorov complexity
1.1. Definition and main properties
1.2. Algorithmic properties
Chapter 2. Complexity of pairs and conditional complexity
2.2. Conditional complexity
2.3. Complexity as the amount of information
Chapter 3. Martin-Löf randomness
3.2. The Strong Law of Large Numbers
3.3. Effectively null sets
3.4. Properties of Martin-Löf randomness
3.5. Randomness deficiencies
Chapter 4. A priori probability and prefix complexity
4.1. Randomized algorithms and semimeasures on ℕ
4.2. Maximal semimeasures
4.4. A digression: Machines with self-delimiting input
4.5. The main theorem on prefix complexity
4.6. Properties of prefix complexity
4.7. Conditional prefix complexity and complexity of pairs
Chapter 5. Monotone complexity
5.1. Probabilistic machines and semimeasures on the tree
5.2. Maximal semimeasure on the binary tree
5.3. A priori complexity and its properties
5.4. Computable mappings of type Σ→Σ
5.6. Levin–Schnorr theorem
5.8. Effective Hausdorff dimension
5.9. Randomness with respect to different measures
Chapter 6. General scheme for complexities
6.2. Comparing complexities
6.3. Conditional complexities
6.4. Complexities and oracles
Chapter 7. Shannon entropy and Kolmogorov complexity
7.2. Pairs and conditional entropy
7.3. Complexity and entropy
Chapter 8. Some applications
8.1. There are infinitely many primes
8.2. Moving information along the tape
8.3. Finite automata with several heads
8.4. Laws of Large Numbers
8.5. Forbidden substrings
8.6. A proof of an inequality
8.7. Lipschitz transformations are not transitive
Chapter 9. Frequency and game approaches to randomness
9.1. The original idea of von Mises
9.2. Set of strings as selection rules
9.3. Mises–Church randomness
9.6. A digression: Martingales in probability theory
9.7. Lower semicomputable martingales
9.8. Computable martingales
9.9. Martingales and Schnorr randomness
9.10. Martingales and effective dimension
9.11. Partial selection rules
9.12. Non-monotonic selection rules
9.13. Change in the measure and randomness
Chapter 10. Inequalities for entropy, complexity, and size
10.1. Introduction and summary
10.3. Construction of a uniform set
10.4. Uniform sets and orbits
10.5. Almost uniform sets
10.7. Combinatorial interpretation: Examples
10.8. Combinatorial interpretation: The general case
10.9. One more combinatorial interpretation
10.10. The inequalities for two and three strings
10.11. Dimensions and Ingleton’s inequality
10.12. Conditionally independent random variables
10.13. Non-Shannon inequalities
Chapter 11. Common information
11.1. Incompressible representations of strings
11.2. Representing mutual information as a string
11.3. The combinatorial meaning of common information
11.4. Conditional independence and common information
Chapter 12. Multisource algorithmic information theory
12.1. Information transmission requests
12.2. Conditional encoding
12.3. Conditional codes: Muchnik’s theorem
12.4. Combinatorial interpretation of Muchnik’s theorem
12.5. A digression: On-line matching
12.6. Information distance and simultaneous encoding
12.7. Conditional codes for two conditions
12.8. Information flow and network cuts
12.9. Networks with one source
12.10. Common information as an information request
12.11. Simplifying a program
12.12. Minimal sufficient statistics
Chapter 13. Information and logic
13.1. Problems, operations, complexity
13.2. Problem complexity and intuitionistic logic
13.3. Some formulas and their complexity
13.4. More examples and the proof of Theorem 238
13.5. Proof of a result similar to Theorem 238 using Kripke models
13.6. A problem whose complexity is not expressible in terms of the complexities of tuples
Chapter 14. Algorithmic statistics
14.1. The framework and randomness deficiency
14.3. Two-part descriptions
14.4. Hypotheses of restricted type
14.5. Optimality and randomness deficiency
14.7. A bit of philosophy
Appendix 1. Complexity and foundations of probability
Probability theory paradox
Simple events and events specified in advance
Dynamical and statistical laws
Are “real-life” sequences complex?
Randomness as ignorance: Blum–Micali–Yao pseudo-randomness
A digression: Thermodynamics
Another digression: Quantum mechanics
Appendix 2. Four algorithmic faces of randomness
Face one: Frequency stability and stochasticness
Face four: Unpredictability
Generalization for arbitrary computable distributions