Craig S. Kaplan

Wow, I'm glad the internet enjoyed my silly demo so much. As I mentioned elsewhere, I tip my hat to the people who responded with their past implementations of the same idea.

I wish the students in my undergraduate P5.js course were as enthusiastic about this material as all of you 🙃

In my online undergraduate P5.js course, students are about to begin the module on motion and physics, including a bit of physics simulation using Matter.js. It suddenly occurred to me that I had never seen anybody put together this particular demo before, and I realized it had to be done. Messy source code at https://editor.p5js.org/isohedral/full/vJa5RiZWs.

My region, Kitchener-Waterloo, is often abbreviated KW. I just discovered that there's a perfect Unicode character for that: ㎾. https://unicodeplus.com/U+33BE

I'm not in the Epstein files, though someone else with my name is mentioned once or twice (as part of some US political campaign event). But I do know a few people who are mentioned.

Interestingly, it appears that Epstein was subscribed to the Gathering 4 Gardner mailing list, and went so far as to make plans to attend G4G11 (2014). I was at that event. I don't remember one way or another whether he was there, but it's certainly possible.

The time has come. Me, Bill Murray, and a sweet vermouth on the rocks with a twist. Happy Groundhog Day.

January 31: GLSL day. Create an artwork using only shaders.

I'm going to cheat a bit and share a work-in-progress image from a forthcoming paper by my PhD student Brian Do. This is a hyperbolic version of Kitaoka's Rotating Snakes illusion. The whole thing is rendered in real time in a browser-based app, using shaders. Pre-print and interactive tool coming soon. #genuary #genuary2026

There are a few different notations that are used to describe "regular" tilings (where we use "regular" in the informal sense of "simple arrangement of copies of a single shape"). The most important are probably Grünbaum and Shephard's incidence symbols for isohedral tilings, and Heesch and Kienzle's primitive tiling types. A system developed by Bigalke and Wippermann in the 1990s is intermediate between the other two.

Talking to Doris Schattschneider last year, we realized that there doesn't seem to be a convenient cross reference online that shows how these systems relate to each other. So we created one: https://isohedral.ca/isohedral-tiles-tilings-and-notations/.

We'll probably put this up on arXiv eventually, on the off chance that anybody wants to cite it. But the web page includes a few nice interactive features that give it independent value. We hope this is a useful resource!