Term Project CS 591 . 003 Fall 02 UNM

This report describes the design and results of a series of experiments in complexity in physics and critical phenomena. Experiments included the following: 1. Ising model simulations where the critical temperature of the phase transition and the correlation length were measured on 2D lattices. 2. Percolation simulations implented using the union find algorithm that estimate the size of the giant cluster and the critical exponents. 3. Experiments observing a phase transition in the complexity of NP-hard satisfiablity problems using the davis-putnam procedure on random 3-SAT instances. This report also doubles as a manual to the software written in [ANSI CL] 1 : An aim of the project was to construct a framework of reusable components for running, visualizing, and logging the results, of experiments. The components are implemented as a bunch of CLOS classes and generic function protocols 1 Written and tested on current versions (18d+) of CMU Common Lisp[CMUCL]. When available, the Common Lisp Interface Manager [CLIM] is used to display primitive graphics. The plots were done in gnuplot.