Diana Davis’s Beautiful Pentagons: https://blogs.scientificamerican.com/roots-of-unity/diana-davis-beautiful-pentagons/

I briefly mentioned her regular-pentagon billiards-trajectory art in https://mathstodon.xyz/@11011110/101530712079779913 but now Evelyn Lamb has a much more detailed column on her and her work.

What happens when half a cellular automaton runs Conway's Game of Life and the other half runs a rolling version of Rule 30 pushing chaos across the border? https://www.youtube.com/watch?v=IK7nBOLYzdE, via https://news.ycombinator.com/item?id=22723884

I wish I could see a larger scale of time and space to get an idea of how far the effects penetrate. If the boundary emitted gliders at a constant rate they'd collide far away in a form of ballistic annihilation but the boundary junk and glider-collision junk makes it more complicated.

Today at lunch, I've learned about the Trash Compaction problem: Can you push objects on a grid into the compact shape of a rectangle if you're only allowed to push all objects from one side simultaneously. Akitaya, Aloupis, Löffler, and Rounds showed that the problem is NP-complete.

The fun variant of this problem talks about pushing around coconuts with a giant coconut pusher... Here are some neat slides: http://www.staff.science.uu.nl/~loffl001/publications/slides/trash_compaction.pdf

Mathematician working mostly in three-dimensional geometry and topology, and mathematical artist working mostly in 3D printing and virtual reality.

Joined Apr 2017