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##### Life Variants

Penrose tilings and Ready

##### Life Variants

My apologies for the lack of recent postings. There are rumours that the LifeNews server may be turning off in the immediate future, so I was tentative about uploading something new. Nevertheless, Andrew Trevorrow convinced me that this deserves to be published on ConwayLife.com, and I understand this to currently be the most direct way of doing so.

The developers of Golly have recently turned their attentions to creating a new piece of software capable of supporting reaction-diffusion systems and cellular automata on arbitrary meshes. This has been discussed on Complex Projective 4-Space and The Aperiodical, amongst other places.

There has also been some work on cellular automata on Penrose tilings. Nick Owens and Susan Stepney investigated B3/S23 a while ago, writing a chapter about the topic in Adamatzky's *Game of Life Cellular Automata*. This summer, a couple of related, independent and almost simultaneous discoveries were made. One of these was a weakly universal cellular automaton on a Penrose tiling; the other was a glider.

The glider attracted a lot more attention, not least because a $100 prize was offered for its discovery. Again, this was mentioned on Complex Projective 4-Space, New Scientist and The Aperiodical. Even more recently, it was investigated on the kite-and-dart Penrose tiling, where it follows fractal paths and symmetrical loops. An image is displayed below:

The lengths of loops (half the period of the resulting oscillators, since the glider is c/2) are tabulated in the sequence A215878 of the Online Encyclopedia of Integer Sequences.