Dave Richeson

Granny Life Community Build Project Granny Life

Math nerds and crafty geeks! You are invited to crochet a granny square based on a cellular automaton for the Granny Life project at www.grannylifecrochet.com.

Your work could end up in an art exhibit in Paris! There are plenty of motifs still available to claim :)

#mathsky #crochet 🧶

Looking back at the example, it does have the Borromean rings as a boundary as claimed, but it is not a Seifert surface since it is not orientable (it is "one sided" like a Möbius band).

community are largely craft, design, models, and visualization, not fine art... These characteristics do not make an object less interesting or less valuable within our community, but they may distance the object from accepted notions of fine art."

with so many true excellent fine artists:

"The bigger issue in the world of math/art, I feel, is that much of what is presented in our art exhibitions and publications is not truly 'fine art'... The works presented in the Bridges Conference, the JMM exhibition, and many publications of the math/art

I finally read this 2024 article by George Hart in the Notices of the AMS, "What Can We Say About 'Math/Art'?" www.ams.org/notices/2024...

He puts his finger on something that has made me uncomfortable or feel like an impostor when I say that I do mathematical art, when I know and am friends

A Seifert surface for the figure-eight knot: Give two strips of paper two half-twists in opposite directions. Tape the bands together cross-ways as shown. The boundary is a figure-eight knot.

On my X-mas wish list.

By the way, Henry, your reply did not show up in my notifications. It still doesn't. I didn't see it until someone replied. I don't know why that would be (??).

Good point. I wonder what role the authors had in choosing the cover art.

These thoughts were inspired by @gelada.bsky.social's talk and artwork at this year's Bridges conference. gallery.bridgesmathart.org/exhibitions/...

This is a photo of a tree that fell on campus during a summer storm. I wonder if there's an interesting conversation we could have with multivariable calculus students about tree rings. Tree rings are level curves. What's the function? What does the gradient vector tell us? Etc.

My wife and daughter just visited a friend in Spain, and they went to the Alhambra. They brought me back this souvenir! A 470 page book about the mathematics of the Alhambra! Very cool. They know me.

M.C. Escher name drop in the Amazon Prime series, Ballard:

"I just can't wrap my head around it. I feal like I'm in one of those Escher drawings where everything holds togetehr, but nothing makes sense."

The US will stop making pennies in 2026, which got me thinking about what to do with a giant collection of too-expensive, low-value coins. Here's what I made with them.

Tom Lehrer, Musical Satirist With a Dark Streak, Dies at 97

NY Times obit www.nytimes.com/2025/07/27/a...

YouTube video by FreddeTl Tom Lehrer - Lobachevsky

RIP Tom Leher (1928–2025)
www.youtube.com/watch?v=UQHa...

It is iOrnament Pro. It is in the app store

Thank you!

Yeah. It is like magic each time I draw even a random squiggle.

The final "artwork."

Jürgen Richter-Gebert was one of the keynote speakers at Bridges. He spoke about the iOrnament software he wrote for the iPad. I just downloaded it and made this design in 50 seconds. Wow!

I did! I’m sorry that you were unable to attend in person!

I remember seeing this a few years ago. Very cool!

GitHub - loopspace/Seifert: LaTeX+TikZ code for cut-and-paste Seifert surfaces. LaTeX+TikZ code for cut-and-paste Seifert surfaces. - loopspace/Seifert

Nice! You might like this LaTeX project I once made for designing such things.

github.com/loopspace/Se...

I decided to try one more. The boundary of this paper Seifert surface is the Borromean rings (red is over green, green is over blue, and blue is over red).

by taking the long part of the strip and making a "double-twisted cylinder"—like a Möbius band with two half twists. Then, I gave the extra piece a single half twist.

Aside: I love working with paper, but one challenge is that it doesn't twist very nicely.

Shiying Dong gave a nice presentation at Bridges (her paper: www.archive.bridgesmathart.org/2025/bridges...) on crocheting Seifert surfaces starting with centerline graphs. This morning, I tried using a similar technique with paper. Here's my third attempt. The boundary is a trefoil knot. I began

This reminds me of a dinner after a research seminar when I was a grad school. They ended up with too much money for the bill, and after a long time, realized that the person counting, a distinguished mathematician who shall not be named, did not count herself.

This is the Eye Filmmuseum's roof from above. I took it to examine the pattern later. The roof tiles are rhombi and trapezoids made from two rhombi.

Some odds-and-ends.