Complex Systems Reading Group

Summer, 2001

During the spring and summer terms we will meet every Wednesday at 4pm outside at Dominick's (on Monroe St. behind the Law Quadrangle).

Meeting on Wed., May 2, 4pm, Dominick's Our first meeting will be this Wednesday, May 2, where we will discuss:

Chaitin, G. J. (2000). A century of controversy over the foundations of mathematics. Complexity 5(5): 12-21 (May /June 2000).

This is a very well-written transcript of a talk given by Chaitin on the relationship between computer science, logic, and mathematics, and about randomness in mathematics.

Please let me know if you have suggestions for other readings over the summer.

Based on last Wednesday's fact-finding expedition, we'll try meeting at Cafe Felix in the fall. It's a bit quieter than Old Town, and they serve coffee as well as good food and beer. Thanks to Bill Tozier for the suggestion!

Meeting on Wed., May 9, 4pm, Dominick's

At our meeting this Wednesday, May 9 at 4pm at Dominick's (on Monroe St.), we will discuss:

Padgett, John F. (2000). Modeling Florentine republicanism. SFI Working Paper 01-02-008.
gzipped PostScript: http://www.santafe.edu/sfi/publications/Working-Papers/01-02-008.ps.gz
PostScript: http://www.santafe.edu/sfi/publications/Working-Papers/01-02-008.ps
PDF: http://www.santafe.edu/sfi/publications/Working-Papers/01-02-008.pdf

Abstract: The following model of political process is intended to be a moderately realistic representation of Florentine republicanism, during the period of the Renaissance (ca. 1300-1500). The model is composed of two parts: (a) patronage - namely, the building up of partisan networks through the exchange of office-based favors, and (b) policy - namely, the collective deliberation and choice of "public goods" for Florence, in the Priorate (i.e., the city-council governing body). It was the tension and interplay between these two modes of governance, I contend, that produced Renaissance Florence's distinctively turbulent, and creative, history of party formation and constitutional design. This memo proceeds in three sections: the official structure of the Florentine state, the patronage networks that grew up through these offices, and the "sacred" institutions at the center that may or may not have transcended patronage.

Meeting on Wed. 5/16, 4pm, Dominick's

An unresolved question in my mind, at least, is the relation between entropy, information, and complex systems. This Wednesday, May 16 at 4pm at Dominick's we'll try to make some headway on this together. And for those of us whose heads hurt when we think about entropy, there's always beer. So please come help fend off the heat death of the universe for another day. As always, feel free to stop by even if you don't have time to read the paper.

Crutchfield, James P., and David P. Feldman. (2001). Synchronizing to the environment: Information theoretic constraints on agent learning. SFI working paper 01-03-020. Submitted to Physics Review E.

http://www.santafe.edu/sfi/publications/Working-Papers/01-03-020.pdf http://www.santafe.edu/sfi/publications/Working-Papers/01-03-020.ps http://www.santafe.edu/sfi/publications/Working-Papers/01-03-020.ps.gz

Abstract:

We show that the way in which the Shannon entropy of sequences produced by an information source converges to the source's entropy rate can be used to monitor how an intelligent agent builds and effectively uses a predictive model of its environment. We introduce natural measures of the environment's apparent memory and the amounts of information that must be (i) extracted from observations for an agent to synchronize to the environment and (ii) stored by an agent for optimal prediction. If structural properties are ignored, the missed regularities are converted to apparent randomness. Conversely, using representations that assume too much memory results in false predictability.

Those who want more background can read:

Crutchfield, James P., and David P. Feldman. (2001). Regularities unseen, randomness observed: Levels of entropy convergence. SFI working paper 01-02-012.

http://www.santafe.edu/sfi/publications/Working-Papers/01-02-012.pdf http://www.santafe.edu/sfi/publications/Working-Papers/01-02-011.ps http://www.santafe.edu/sfi/publications/Working-Papers/01-02-011.ps.gz

Meeting on Wed., May 23 at 4pm at Dominick's (Monroe St.)

Newman, Mark. (1999). Small worlds: The structure of social networks. SFI Working Paper 99-12-080. To appear in Complexity.

http://www.santafe.edu/sfi/publications/Working-Papers/99-12-080.pdf http://www.santafe.edu/sfi/publications/Working-Papers/99-12-080.ps http://www.santafe.edu/sfi/publications/Working-Papers/99-12-080.ps.gz

Abstract: Experimentally it has been found that any two people in the world, chosen at random, are connected to one another by a short chain of intermediate acquaintances, of typical lenth about six. This phenomenon, colloquially referred to as the "six degrees of separation", has been the subject of a considerable amount of recent research and modeling, which we review here.