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I'm a computer scientist at the University of California, Irvine, interested in algorithms, data structures, discrete geometry, and graph theory.
I'm a computer scientist at the University of California, Irvine, interested in algorithms, data structures, discrete geometry, and graph theory.
It's that time of the year when the plum blossoms in the alley behind my office catch the late afternoon sunlight
I'm a computer scientist at the University of California, Irvine, interested in algorithms, data structures, discrete geometry, and graph theory.
Indonesian government blocks #Wikipedia editors from logging in over lack of official registration of the site with the government: https://rri.co.id/voice-of-indonesia/technology/2233098/wikipedia-users-in-indonesia-now-cannot-log-in-why
I'm a computer scientist at the University of California, Irvine, interested in algorithms, data structures, discrete geometry, and graph theory.
MacTeX TeX Live 2026 now available: https://www.tug.org/mactex/mactex-download.html
You probably need this if you use Macs and are working on generating tagged pdf from LaTeX for accessibility. You might want to avoid this if you rely heavily on cleveref, which is broken in recent TeX Live releases.
I'm a computer scientist at the University of California, Irvine, interested in algorithms, data structures, discrete geometry, and graph theory.
A regular pentagon has five symmetry axes through one corner and its center point. Its five diagonals cross to form a smaller nested pentagon. Kevin Grace has called these ten lines (symmetry axes and diagonals) and eleven points (nested pentagon corners and center) the "Betsy Ross configuration" because of the five-point stars on the US flag. Its construction necessarily involves the square root of five, because the diagonals of a regular pentagon are longer than its sides by a factor of the golden ratio, \((1+\sqrt5)/2\). It is "projectively rigid": every ten lines and eleven points with the same pattern of point-line incidences comes from a projective transformation of the regular pentagon. Therefore, in any other drawing of points and lines in this pattern, \(\sqrt5\) still appears, in the cross ratio of distances among four collinear points. Points with rational numbers as coordinates would have rational cross-ratios, so the Betsy Ross configuration cannot be drawn with rational coordinates.
If you remove from this configuration one symmetry axis and the two pentagon corners that it passes through, the remaining nine points and nine lines form the Perles configuration (https://en.wikipedia.org/wiki/Perles_configuration). It is again projectively rigid and is the smallest system of points and lines that requires irrational coordinates. It was used by Micha Perles to construct 8-dimensional convex polytopes that also require irrational coordinates; other applications involve counting point-line incidences in points with forbidden configurations, the complexity of recognizing visibility graphs of point sets, and proving irrationality for certain graph drawing problems.
Now a Good Article on Wikipedia.
I'm a computer scientist at the University of California, Irvine, interested in algorithms, data structures, discrete geometry, and graph theory.
Remembering Joe Halpern, https://blog.arxiv.org/2026/02/27/remembering-joe-halpern/, focuses on Joe's pivotal role in founding and guiding the CS section of the arXiv.
I'm a computer scientist at the University of California, Irvine, interested in algorithms, data structures, discrete geometry, and graph theory.
New blog post: Making accessible LaTeX talk slides with ltx-talk, https://11011110.github.io/blog/2026/03/01/making-accessible-latex.html
I'm a computer scientist at the University of California, Irvine, interested in algorithms, data structures, discrete geometry, and graph theory.
Flip distance of triangulations of convex polygons / rotation distance of binary trees is NP-complete: https://arxiv.org/abs/2602.22874, Joseph Dorfer
An answer to a well-known problem that was implicit in the STOC 1986 work of Sleator, Tarjan, and Thurston on the extreme values of flip distance / rotation distance (https://doi.org/10.1145/12130.12143) and already explicit by 1988 in the (incorrect) claims of a polynomial time algorithm of Křivánek (https://doi.org/10.1007/bfb0015934 theorem 7).
I'm a computer scientist at the University of California, Irvine, interested in algorithms, data structures, discrete geometry, and graph theory.
According to the Bonnet theorem (https://en.wikipedia.org/wiki/Bonnet_theorem), describing the surface distances and principal curvatures of a smooth 2d surface is enough to determine a local embedding of the surface (an immersion) into 3d. A related result by H. Blaine Lawson and Renato de Azevedo Tribuzy shows that using mean curvature instead of the principle curvatures is almost enough: for a smooth compact surface and non-constant mean curvature, there can be at most two immersions. The recent paper "Compact Bonnet pairs: isometric tori with the same curvatures" (Bobenko, Hoffmann & Sageman-Furnas, Pub. Math. de l'HÉS 2025, https://doi.org/10.1007/s10240-025-00159-z) shows that the case of two immersions can actually happen: there are pairs of immersed tori in 3d with different shapes in 3d but the same surface distances and mean curvatures. Recently described in Quanta: Two Twisty Shapes Resolve a Centuries-Old Topology Puzzle, https://www.quantamagazine.org/two-twisty-shapes-resolve-a-centuries-old-topology-puzzle-20260120/
I'm a computer scientist at the University of California, Irvine, interested in algorithms, data structures, discrete geometry, and graph theory.
Subdivisions of a triangle into smaller similar triangles lead to new substitution tilings of the plane based on the plastic and superplastic constants: https://blog.wolfram.com/2019/03/07/shattering-the-plane-with-twelve-new-substitution-tilings-using-2-phi-psi-chi-rho/ (Ed Pegg, Wolfram Insights)
I'm a computer scientist at the University of California, Irvine, interested in algorithms, data structures, discrete geometry, and graph theory.
National Institute of Standards and Technology appears to be squeezing out "foreign-born researchers": https://arstechnica.com/science/2026/02/major-government-research-lab-appears-to-be-squeezing-out-foreign-scientists/
The language used here is especially concerning: we should not be hobbling our research institutions by limiting their researchers to being US citizens, but requiring US birth goes far beyond even that.
I'm a computer scientist at the University of California, Irvine, interested in algorithms, data structures, discrete geometry, and graph theory.
I'm a computer scientist at the University of California, Irvine, interested in algorithms, data structures, discrete geometry, and graph theory.
I don't know the story here, but when parallel papers claiming the same strong result come out simultaneously on arXiv, it's usually not a coincidence:
"An \(n^{2+o(1)}\) Time Algorithm for Single-Source Negative Weight Shortest Paths", Sanjeev Khanna & Junkai Song, https://arxiv.org/abs/2602.16638
"Bellman-Ford in Almost-Linear Time for Dense Graphs", George Z. Li, Jason Li, & Junkai Zhang, https://arxiv.org/abs/2602.16153
I'm a computer scientist at the University of California, Irvine, interested in algorithms, data structures, discrete geometry, and graph theory.
The circle packing theorem (https://en.wikipedia.org/wiki/Circle_packing_theorem): every planar graph can be represented by the tangencies of a system of non-overlapping circles.
This theorem was proved by Koebe in 1936, and popularized in the 1980s by Fields medalist William Thurston as a discrete analogue to conformal mapping and uniformization. Its Wikipedia article was created by Oded Schramm in 2008, not long before his untimely mountaineering death. In his own research, Schramm found deep analogies between random walks on circle packings and Brownian motion. My interests in circle packing relate to its use in drawing graphs, constructing polyhedra for given graphs, modeling soap bubble foams, and finding planar separators. And others have found even more varied applications from the study of discrete symmetry groups of hyperbolic space to methods for visualizing the functional areas of the human brain, spread out into a flattened map.
Now a Good Article on Wikipedia.
I'm a computer scientist at the University of California, Irvine, interested in algorithms, data structures, discrete geometry, and graph theory.
The cleveref apocalypse is on us: The cleveref LaTeX package is long-unmaintained and breaks on recent LaTeX versions, and an arXiv update to TeXlive means that we can no longer keep limping along using old-enough versions of TeX to avoid the problem. I haven't yet tried it but my bookmarked solution is to switch to zref-clever: https://tex.stackexchange.com/questions/733714/migration-from-cleveref-to-zref-clever
I'm a computer scientist at the University of California, Irvine, interested in algorithms, data structures, discrete geometry, and graph theory.
RE: @highergeometer@mathstodon.xyz
Good to see there are still people online crazy enough to think that emulating a GameBoy using arbitrary precision arithmetic implemented purely through compass and straightedge constructions is a good idea
I'm a computer scientist at the University of California, Irvine, interested in algorithms, data structures, discrete geometry, and graph theory.
Archive.today / archive.is / archive.ph etc initiates a DDOS attack against a blogger they accused of doxing them (https://gyrovague.com/2026/02/01/archive-today-is-directing-a-ddos-attack-against-my-blog/, via https://lobste.rs/s/z0mdor), sparking calls to blacklist them from reference link archiving on Wikipedia: https://en.wikipedia.org/wiki/Wikipedia:Village_pump_(technical)#Deprecating_and_blacklisting_archive.today
