
Halloween linkage
 Quasiperiodic bobbin lace patterns (, via). Veronika Irvine, Therese Biedl, and Craig S. Kaplan make aperiodic tilings in fiber arts.

Don't walk
Like many UC Irvine faculty I live in University Hills, a faculty housing complex associated with UC Irvine. It’s a great place to live: the prices are significantly lower than the surrounding area, I like my neighbors, and I love living so close to my office (ten minutes by foot) that I can walk to work instead of having to deal with the twin headaches of Southern California traffic and university parking.

MathJax 3 in Jekyll and Kramdown
The mathematical equations in my blog posts, and the ones you see on many other web sites, are formatted with MathJax, a JavaScript library that lets web developers write LaTeX formulas and turns them within your browser into nicely formatted math. The web pages of my blog are generated by Jekyll, a static web site generation system (meaning that it doesn’t go querying a database for its content, they are just web pages stored in files somewhere). I can write my posts in more than one format, but since the April 2017 LiveJournal apocalypse I’ve been writing them using kramdown, a system built into Jekyll for transforming markedup text files into html ready for browsers to read and display. And so far mostly those different systems have been getting along really well together. Kramdown knows about MathJax and can handle equations in its input without trying to interpret their syntax as kramdown codes, Jekyll only needs me to modify a template somewhere so that my blog pages include an invocation of the MathJax library, and MathJax in your browser happily formats the equations in my posts. But recently, the MathJax people released MathJax version 3.0.0, and that doesn’t work so well with Jekyll and Kramdown. Despite some difficulty, I seem to have gotten them working again. So I thought it might be helpful to post here what went wrong and how I fixed it, in case others run into the same issues.

From one fold to another
If an origami crease pattern tells you where to put the folds, but not which way to fold them, you may have many choices left to make. A familiar example is the square grid. You can pleat (accordionfold) the horizontal lines of the grid, and then pleat the resulting folded strip of paper along the vertical lines; the result will be that each horizontal line is consistently a mountain fold or a valley fold, but each vertical line has folds that alternate between mountain and valley. Or you could pleat the vertical lines first, and then the horizontal lines, getting a different folded state. There are many other choices beyond these two.

Linkage
 Spanning Trees with Low (Shallow) Stabbing Number () is the master’s thesis of Johannes Obenaus at the Free University of Berlin and ETH Zürich. The stabbing number of a tree is how many edges a line can cross. Any points in have a tree with stabbing number , useful in some data structures. The thesis includes a solution to Open Problem 17.5 of my book Forbidden Configurations in Discrete Geometry: removing points from a point set might cause the minimum stabbing number of a spanning tree to increase.

Hardness of planar Hamiltonian decomposition and linear arboricity
I was getting ready to start writing a paper proving that Hamiltonian decomposition and linear arboricity are both complete for planar graphs of maximum degree four. But then I realized that there’s a trivial proof, based on known results:

Drawing clustered graphs of bounded width
In a paper from last year on clustered planarity, with Giordano Da Lozzo, Mike Goodrich, and Sid Gupta, we provided subexponentialtime algorithms for arbitrary instances, and fixedparameter tractable algorithms for instances whose embedded width and number of clusters are both bounded.

Linkage
 Proceedings of the 27th International Symposium on Graph Drawing and Network Visualization (GD 2019) (). As in recent years, Graph Drawing is making an openaccess version of their complete proceedings through arXiv, mirroring (except for minor typographic details) the official proceedings to be published through Springer LNCS. One advantage of the arXiv version is that in many cases appendices or longer versions of the papers are also available.

Congratulations, Dr. Mamano!
Today Nil Mamano successfully passed his dissertation defense. Nil has been a doctoral student at UCI, jointly supervised by Mike Goodrich and myself.

One thousand women of STEM!
Today, by my (likely inaccurate) count, I created my 1000th Wikipedia article on women in mathematics, statistics, computer science, and other areas of science and technology. This is something I’ve been doing since 2008, with several goals in mind. Of course, I want to improve Wikipedia’s coverage in an area that has historically not been covered well. But I also want to counter the perception that there have only been a few heroic figures in this area (say, Hypatia, Lady Lovelace, and Emmy Noether) and show that, instead, it is becoming commonplace (although not yet frequent enough) for men and women to work as equals in science and technology. I want it to be the case that, when readers go to Wikipedia to see who did what in these areas, the names that they see include a representative sample of women, and that those readers can go to articles on those women to find out more about what they went through to do what they did.
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