ysp_2003, notes, pictures and experiments which I generated as part of the NSF Young Scholars Program at Florida State University. Our group was led by Professor Janet Peterson, and included the students Kevin Mcleod and Patrick Neary.
Our project focussed on cellular automata.
One issue that came up with one dimensional cellular automata was the claim that a few rules were suitable for use as random number generators. In fact, supposedly, the program Mathematica uses the cellular automaton called "rule 30" to do random number calculations. Using Visual Basic, the students programmed up a version of rule 30 and wrote out the "center bit" of the array of cells for hundreds of thousands of steps. Then, using a C++ program called BITS_TO_UI, the text file of bits was converted into a binary file of 32-bit integers, to be passed to Marsaglia's DIEHARD program, to be tested for "randomness".
For the second phase of the project, we wanted to look at a two dimensional cellular automaton. We found an article by A K Dewdney, in Scientific American for August 1988, in which he discussed something called the "hodge podge" machine. This was a 2D CA, with some parameters, that could be thought of as a collection of cells with a tendency to get "infected". The infection follows certain rules that tend to make a cell become more and more infected until it actually becomes "ill". On the next step, an ill cell goes back to being completely healthy.
Dewdney said that for certain values of the parameters, the cellular automaton would mimic the waves of color that are seen in the Belousov-Zhabotinsky chemical reaction. And in fact, there is an analogy, because there is a catalytic reaction going on; a cell getting more and more infected can be regarded as building up to some critical value that allows the reaction to take place, after which it will naturally drop back down to the rest state.
Kevin and Patrick searched the web, and were able to find a C program with an elaborate implementation of the hodge podge machine; however they could not get it to compile on their PC. Since we were running out of time, I volunteered to perform surgery on the program with a sledge hammer. The next day, we had a drastically simplified program with one enormous advantage over the fancy version: my version compiled and ran. (And it did so on both my Unix system and Kevin and Patrick's PC.) The source code of this dopey Opie version is available in hodge.c
Kevin and Patrick were able to view the binary PPM graphics files output by the program by downloading and installing GIMP, the GNU Image Manipulation Program. Once they adjusted the parameters a bit, they were seeing the waves of infection that Dewdney reported.
On the last day of the program, Kevin and Patrick prepared a poster in PowerPoint format, and presented it to the other participants in the program. They also wrote up a report about their work.
Last revised on 19 May 2020.