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Regularities unseen, randomness observed: levels of entropy convergence
James P Crutchfield1, David P Feldman
1Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, New Mexico 87501, USA. chaos@santafe.edu
Chaos (Woodbury, N.Y.)
|April 5, 2003
Summary
This study explores how Shannon entropy (a measure of randomness) in data sequences relates to an information source's true entropy rate. It introduces methods to quantify memory and prediction difficulty in complex systems.
Area of Science:
- Information Theory
- Computational Complexity
- Statistical Mechanics
Background:
- Understanding information source behavior is crucial for data analysis and prediction.
- Existing methods often struggle with short sequences and complex system dynamics.
- The relationship between observed randomness and underlying process structure requires further investigation.
Purpose of the Study:
- To analyze the convergence of Shannon entropy to an information source's entropy rate.
- To develop information-theoretic measures for apparent memory and synchronization difficulty.
- To investigate the impact of process structure on entropy convergence and apparent randomness.
Main Methods:
- Synthesized phenomenological approaches using successive derivatives of the Shannon entropy growth curve.
- Defined and analyzed 'transient information' for measuring synchronization difficulty in Markov processes.
- Performed numerical and analytical determinations of entropy growth curves for various stochastic and deterministic processes.
Main Results:
- Developed natural measures for apparent memory and information required for optimal prediction and synchronization.
- Proved a relationship between transient information and total uncertainty during synchronization for Markov processes.
- Demonstrated that ignoring structural properties can convert missed regularities into apparent randomness, especially with short sequences.
Conclusions:
- The study provides a framework for understanding information source dynamics through entropy convergence.
- Apparent memory and synchronization difficulty can be quantified using information-theoretic measures.
- Entropy convergence behavior is intrinsically linked to a process's underlying computational structure.