Three-Toed Sloth

Cover Model

Hot off the presses:

Cosma Rohilla Shalizi, Kristina Lisa Shalizi and Robert Haslinger, "Quantifying Self-Organization with Optimal Predictors", Physical Review Letters 93 (2004): 118701 [link]

Abstract: Despite broad interest in self-organizing systems, there are few quantitative, experimentally applicable criteria for self-organization. The existing criteria all give counter-intuitive results for important cases. In this Letter, we propose a new criterion, namely, an internally generated increase in the statistical complexity, the amount of information required for optimal prediction of the system's dynamics. We precisely define this complexity for spatially extended dynamical systems, using the probabilistic ideas of mutual information and minimal sufficient statistics. This leads to a general method for predicting such systems and a simple algorithm for estimating statistical complexity. The results of applying this algorithm to a class of models of excitable media (cyclic cellular automata) strongly support our proposal.

I trust that everyone reading this will drop what they're doing and go read our paper right now. If you're so unfortunate as to not have a subscription to PRL, you write me for a copy, or, if you can force yourself to wait until the 13th, download it from the arxiv (nlin.AO/0409024).

Getting in to the top magazine for the first time is pretty cool, but being put on the cover as well might turn some people's heads. Rest assured, however, that, despite my new fame and prestige, Three-Toed Sloth will continue to be the same lazy, shrill, self-important source of pedantic obscurity and ivory-tower impracticality it's always been.

All joking aside, I've wanted to do this paper, or something very like it, ever since I took David Griffeath's course on stochastic cellular automata in the spring of 1995, which is when I realized that I had no idea what the word "self-organizing" meant. This was actually the topic of my first real scientific talk, which was somehow accepted as my thesis proposal. It just took me a really long time to figure out how to do this right, and I'd never have been able to actually get it to work without the help of Kris and Rob (who, as befits someone who is a by-word for modesty among his friends, has absolutely no web presence, just papers). Then there was the year we spent between first submitting the paper and finally getting it accepted. (Our referees made some good points, which really improved the paper; also some they rather insisted on.)

Our eye-candy figures were made with Mirek Wojtowicz's excellent free software MCell, which I recommend to anyone interested in cellular automata.

Complexity; Self-Centered