Experiments on reverse perspective: http://paulbourke.net/miscellaneous/reverseperspective/

Recent post by Paul Bourke with a link to a recent video, https://www.youtube.com/watch?v=iJ4yL6kaV1A, "Hypercentric optics" by Ben Krasnow, showing how to achieve reverse perspective physically using a giant Fresnel lens

Sad news from the AMS: Ron Graham has died. See https://www.ams.org/news?news_id=6244

US Department of Homeland Security decides to require foreign students in the US to either attend in-person classes or leave the country: https://www.ice.gov/news/releases/sevp-modifies-temporary-exemptions-nonimmigrant-students-taking-online-courses-during, via https://news.ycombinator.com/item?id=23751931

Or to put it another way, they are pressuring US universities into opening up in-person classes despite the ongoing pandemic, using the threat of taking away all of their foreign students.

Matthew Seymour has done more incredible work in service of the connection game Hex, this time in the form of a beautifully-implemented collection of 500 "white/black to play and win" puzzles of the sort that chess and go enthusiasts take for granted as study tools:

A stained glass window of a Latin square (https://en.wikipedia.org/wiki/Sir_Ronald_Fisher_window) will be removed from Cambridge U. (https://www.theguardian.com/education/2020/jun/27/cambridge-gonville-caius-college-eugenicist-window-ronald-fisher) because it honors prominent eugenicist R. A. Fisher (https://en.wikipedia.org/wiki/Ronald_Fisher).

The window visualizes a nice piece of mathematics, with a long history that surprisingly originates in Korea (predating Euler) but in context among windows celebrating Cambridge luminaries it could not be separated from Fisher's racist history, so it's sad but I think it's the right decision.

This year's London Math Soc. prizewinners: https://www.lms.ac.uk/news-entry/26062020-1657/lms-prize-winners-2020

Via Holly Krieger at https://twitter.com/hollykrieger/status/1276590144628416512, who won one of this years Whitehead Prizes.

For some reason they keep the Louis Bachelier Prize separate from this listing; it's at https://www.lms.ac.uk/prizes/louisbachelierprize

These results have already led me to add to Wikipedia brief articles on Maria Bruna (another Whitehead Prize, https://en.wikipedia.org/wiki/Maria_Bruna) and Pauline Barrieu (Bachelier 2018, https://en.wikipedia.org/wiki/Pauline_Barrieu).

@christianp @ColinTheMathmo My suspicion is that like in https://community.netlify.com/t/enabling-mathjax-without-using-cms/6873/4 the local mathstodon.xyz content security policy is blocking the mathstodon.xyz mathjax script

@christianp @ColinTheMathmo Javascript console is showing lots of error messages "Refused to apply inline style because it violates the following Content Security Policy directive: "style src='self' https://mathstodon.xyz". Either the 'unsafe-inline' keyword, a hash ('...') or a nonce ('nonce-...') is required to enable inline execution.

New blog post: Sorting with integer offsets https://11011110.github.io/blog/2020/06/28/sorting-integer-offsets.html

For inputs \( x_i \) and a parameter \( k \), sorting the set \( \{x_i+j \mid 0\le i\lt n, 0\le j\lt k\} \) more quickly than a pure comparison sort is a nice exercise in radix sorting. But sorting the very similar-looking set \( \{jx_i \mid 0\le i\lt n, 0\le j\lt k\} \) seems much harder. Why? And what does this all have to do with greedy set cover?

QCSP monsters and the demise of the Chen conjecture: https://dl.acm.org/doi/10.1145/3357713.3384232

In STOC'20, Zhuk and Martin show that dichotomy for constraint satisfaction (see https://en.wikipedia.org/wiki/Schaefer%27s_dichotomy_theorem) gets messier for quantified CSP. Chen conjectured that QCSP problems are either in NP or PSPACE-complete, but coNP-completeness can happen for 3 elements and more elements lead to even more classes.

Talk video: https://www.youtube.com/watch?v=c2HjFlcTjQ0

Zhuk just won the Presburger Award: http://eatcs.org/index.php/component/content/article/1-news/2849-the-eatcs-bestows-the-presburger-award-2020

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- https://www.ics.uci.edu/~eppstein/

I'm a computer scientist at the University of California, Irvine, interested in algorithms, data structures, discrete geometry, and graph theory.

Joined Apr 2017