@ccppurcell The number of graphs grows so quickly with the number of vertices that an explicit database of small graphs could only store very small ones, and that might not be enough to distinguish the property you want from many others. That's why I was thinking it would be easier to identify a property from one moderate-sized graph (and a back end that checked which of many properties it had) rather than from smaller graphs (and a back end that looked them up in a database of small graphs).

It's not like it's difficult to make your own out of, you know, paper, but if you want a colorful kit to teach yourself about the Miura-ori and three other folds, this one looks pretty if a little overpriced at $20 for eight sheets of paper: https://www.thisiscolossal.com/2019/05/paper-folding-kit-by-kelli-anderson/

@ccppurcell for oeis there's a short canonical query input that you can usually calculate yourself, the first few terms in that sequence. But for graphs that's less obvious. Maybe you could describe one moderate size graph and the system could run it past various recognizers to find the classes that contain it?

@ccppurcell It doesn't do the automatic lookup thing you describe but you might like http://graphclasses.org/

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?

@_c_perez I can see why this is on vixra rather than arxiv. The scary part is, there are published journal papers more or less indistinguishable from the first part (before it gets to the drinking game).

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.

@JordiGH For most subjects, yes. You need multiple sources that are secondary, cover the subject in-depth, are published in reliable publications, and independent of the subject. But for professors there are more specific guidelines (looking for highly cited papers, major awards, etc; see https://en.wikipedia.org/wiki/Wikipedia:Notability_(academics) ) and some of the argument is whether those criteria should be separate from or on top of the usual secondary sourcing requirements.

@JordiGH Yeah, my to-do list for this weekend is toast too. I've been spending too much time on Wikipedia drama instead. (It's been spread out over half a dozen different discussions mostly related to Wikipedia's coverage of female academics and more generally on how Wikipedia determines whether academics are notable.)

@JordiGH @bstacey If you want a little discussion, you could always try asking https://en.wikipedia.org/wiki/Wikipedia:Biographies_of_living_persons/Noticeboard what if anything more needs to be done to get the like-advertisement tag removed. But bringing yourself to the attention of the various discussion boards (including that one) is often a mistake. They're looking for drama and will go out of their way to find some whether it was already there or not.

Magic angles and superconductivity in twisted graphene (two sheets of hexagonally tiled carbon twisted relative to each other): https://www.quantamagazine.org/how-twisted-graphene-became-the-big-thing-in-physics-20190430/

How combinatorics became legitimate (https://igorpak.wordpress.com/2019/04/26/how-combinatorics-became-legitimate-according-to-laszlo-lovasz-and-endre-szemeredi/): Igor Pak recommends two interesting video interviews with László Lovász and Endre Szemerédi. The whole interviews are quite long but they're broken into 10-minute clips and Igor has picked out the ones relevant to the title.

@axiom For reconfiguration problems, yes.

@henryseg A little light reading...thanks!

New blog post: Playing with model trains and calling it graph theory, https://11011110.github.io/blog/2019/05/02/playing-model-trains.html

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