Re: [math-fun] Life on the Edge

Attempting to break the world record for a late reply... Early last year, Franklin T. Adams-Watters described an interesting cellular automaton defined on the edges of a square grid and asked:

Can anyone find other interesting patterns? It would be especially interesting if someone can find an "airplane gun", which generates airplanes at regular intervals. Any other patterns that move, and any other periodic patterns - especially with a period greater than two - would also be of interest.

Franklin, you'll be glad to hear that Golly 2.0b includes two new rules, one called LifeOnTheEdge and another called LifeOnTheSlope. See life-on-the-edge.rle and life-on-the-slope.rle, both in Patterns/Other-Rules. Andrew