An implementation of the Product Structure Theorem for planar graphs, in Python:

https://github.com/patmorin/lhp

Not exactly industrial-strength, and leans towards simplicity over performance. Still, it can decompose 100k-vertex triangulations in a few seconds. I'm open to feature requests.

New blog post, Hex, books, and queues: https://11011110.github.io/blog/2020/11/10/hex-books-queues.html

And new arXiv preprint, Stack-number is not bounded by queue-number (with Vida Dujmović, Robert Hickingbotham, Pat Morin, and David R. Wood), https://arxiv.org/abs/2011.04195

if you like well-quantified risk info

https://www.erinbromage.com/post/the-risks-know-them-avoid-them

Congratulations to my (now former) student, Luís Fernando Schulz Xavier da Silveira, who successfully defended his PhD thesis titled Turán Triangles, Cell Covers, Road Placement and Train Scheduling on Monday.

This is the first thesis defense I've taken part in where no two participants were in the same room.

Congratulations to our student (cosupervised with Vida Dujmović) Céline Yelle who just masterfully defended her Master's thesis titled Stack Number, Track Number, and Layered Pathwidth.

The thesis contains two results:

1. \(\mathrm{sn}(G) \le 4\mathrm{lpw}(G) \)

2. \(\mathrm{tn}(G)\le 3\) implies \(\mathrm{lpw}(G)\le 4\).

Planar graphs (and related families of graphs) have \((1+o(1))\log n\)-bit adjacency labelling schemes. Equivalently, there is a graph with \(n^{1+o(1)}\) vertices that contains every \(n\)-vertex planar graph as an induced subgraph.

https://arxiv.org/abs/2003.04280

The proof combines our year-old product structure theorem with binary search trees!

> We have computed the very first chosen-prefix collision for SHA-1. In a nutshell, this means a complete and practical break of the SHA-1 hash function, with dangerous practical implications if you are still using this hash function. To put it in another way: all attacks that are practical on MD5 are now also practical on SHA-1. Check our paper here for more details.

And a response from the president of the ACM: https://www.acm.org/about-acm/statement-regarding-open-access

More information about ACM's opposition to mandatory open access of publicly-funded research:

Apparently the ACM has signed onto a letter opposing a US government policy to require the free distribution of all federally funded research. WTF?

https://www.change.org/p/association-for-computing-machinery-acm-support-open-access?signed=true

the American Mathematical Society just published a free ebook called Living Proof, a collection of mathematicians recounting their often turbulent paths to where they are now. i've read a few of the stories and i think this is an amazing read, not just for scholars of math, but for anyone who is doing something where they simply don't feel "smart enough" to succeed. success is often made up of struggle and failure; this can be difficult to remember in our current times.

Professor of Computer Science at Carleton University

Joined Oct 2018