The graphs behind Reuleaux polyhedra (https://arxiv.org/abs/1904.12761),

Luis Montejano, Eric Pauli, Miguel Raggi, Edgardo Roldán-Pensado

These shapes are the intersections of equal-radius balls centered at their vertices; smoothing some edges gives them constant width. Their vertices are the finite point sets with the most diameters. Their vertex-edge graphs are self-dual, unlike other polyhedral graphs. And their vertex-diameter graphs are 4-colorable. Examples include pyramids over odd polygons.

Some actual data on how the subject's gender influences biography creation and deletion on Wikipedia: http://www.generalist.org.uk/blog/2019/gender-and-deletion-on-wikipedia/

Still-existing older articles on women are more likely to have gone through a deletion discussion than men, but we don't know whether more were nominated or equally many nominated but women survived better, and whether the inequality of nominations has lessened recently or the greater nomination rate for women takes longer to kick in and is still prevalent.

Breaking the Bellman-Ford Shortest-Path Bound: https://arxiv.org/abs/1905.01325, Amr Elmasry

Elmasry claims a time bound of \(O(m\sqrt{n})\) for single-source shortest paths in graphs that may have cycles and negative edge weights, but no negative cycles. If correct, this would be a big improvement over the \(O(mn)\) time for Bellman–Ford. However, I got stuck somewhere around Lemma 3 when trying to understand it. Anyone else have better progress?

Matthew Butterick says no to ligatures in programming fonts: https://practicaltypography.com/ligatures-in-programming-fonts-hell-no.html

I tend to agree. They make some things cuter but more things inconsistent. The lack of a short double back arrow in the Fira example is telling. And anyone who expects to see individual characters has to know what font they're displayed in and how it mangles them. But if you like these for your own text editing, whatever. Just show me the ASCII when I have to view it in my browser.

@axiom For reconfiguration problems, yes.

@henryseg A little light reading...thanks!

El poema de los números primos http://feedproxy.google.com/~r/CuadernoDeCulturaCientfica/~3/Lkihbtzy0OE/ #Matemoción

@christianp @blog Thanks for the new Mastodon feed for @aperiodical — but now I'm curious: is there anyway to make a web link to a post from the feed?

Links like https://mathstodon.xyz/web/statuses/102010494286902227 sort of work in that when I go there logged in I see the thread but when I follow the same link not-logged-in I just go directly to the post and not to its thread here.

Network coding yields lower bounds: https://rjlipton.wordpress.com/2019/04/30/network-coding-yields-lower-bounds/

Lipton and Regan report on a new paper by Afshani, Freksen, Kamma, and Larsen (https://arxiv.org/abs/1902.10935) on lower bounds for multiplication. If algorithmically opening and recombining network messages never improves fractional flow, then \(O(n\log n)\) circuit size for multiplication is optimal. But the same lower bound holds for simpler bit-shifting operations, so it's not clear how it could extend from circuits to bignum algorithms.

- Home page
- 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