Friday, June 28, 2019

"Multivariate Spatiotemporal Hawkes Processes and Network Reconstruction"

A new paper of mine just came out in final form. Here are some details.

Title: Multivariate Spatiotemporal Hawkes Processes and Network Reconstruction

Authors: Baichuan Yuan, Hao Li, Andrea L. Bertozzi, P. Jeffrey Brantingham, and Mason A. Porter

Abstract: There is often latent network structure in spatial and temporal data, and the tools of network analysis can yield fascinating insights into such data. In this paper, we develop a nonparametric method for network reconstruction from spatiotemporal data sets using multivariate Hawkes processes. In contrast to prior work on network reconstruction with point-process models, which has often focused on exclusively temporal information, our approach uses both temporal and spatial information and does not assume a specific parametric form of network dynamics. This leads to an effective way of recovering an underlying network. We illustrate our approach using both synthetic networks and networks that we construct from real-world data sets (a location-based social-media network, a narrative of crime events, and violent gang crimes). Our results demonstrate that, in comparison to using only temporal data, our spatiotemporal approach yields improved network reconstruction, providing a basis for meaningful subsequent analysis—such as examinations of community structure and motifs—of the reconstructed networks.

Wednesday, June 26, 2019

Settlers of Combinatorics

And it's still the case that nobody will want your damn sheep!

Tuesday, June 25, 2019

"Nonlinear Excitations in Magnetic Lattices with Long-Range Interactions"

A paper of mine appeared in final form a few days ago. Here are the details.

Title: Nonlinear Excitations in Magnetic Lattices with Long-Range Interactions

Authors: Miguel Molerón, Chris Chong, Alejandro J. Martínez, Mason A. Porter, Panayotis G. Kevrekidis, and
Chiara Daraio

Abstract: We study—experimentally, theoretically, and numerically—nonlinear excitations in lattices of magnets with long-range interactions. We examine breather solutions, which are spatially localized and periodic in time, in a chain with algebraically-decaying interactions. It was established two decades ago (Flach 1998 Phys. Rev. E 58 R4116) that lattices with long-range interactions can have breather solutions in which the spatial decay of the tails has a crossover from exponential to algebraic decay. In this article, we revisit this problem in the setting of a chain of repelling magnets with a mass defect and verify, both numerically and experimentally, the existence of breathers with such a crossover.

Monday, June 24, 2019

The Fastest E-Mailer in the West

I sometimes respond to e-mails before they're event sent. :P

Thursday, June 20, 2019

Digital Archæoludology: Studying Ancient Games with Machine Learning

Digital Archæoludology is a new field that concerns the computational study of ancient game using tools like machine learning. Very cool!

Here is the arXiv paper that led to the above popular piece.

Game on!

Tuesday, June 18, 2019

Monday, June 17, 2019

The First Hipster?

(Tip of the cap to Nicholas Christakis.)

Sunday, June 16, 2019

Jenny's Constant

How did I not know this? There is a Jenny's constant (for real!)!

As quoted in the above entry in the Online Encyclopedia of Integer Sequences:

First few digits reproduce the digits of the phone number in the song "867-5309/Jenny" performed by Tommy Tutone.

The next digit is a 0, and the following 4 digits (1, 9, 8, 1) are the year the song was recorded (1981). (Noticed by Rob Johnson of the forums)

(Tip of the cap to Nalini Joshi. Nalini's tweet included a link to this old xkcd (which I had forgotten about, and I don't think I had ever followed the rabbit hole about Jenny's constant.)

UCLA's 2019 Mathematics Commencement Ceremony

As you can see from the short video below, this is how we do things in the UCLA mathematics commencement ceremony.

(I am the one in bright red. It's because of my Cornell doctoral degree, but these are almost almost Somerville colors. You can tell the birds from the colors of their feathers.)

Many undergrads from my courses, as well as ones who are doing research projects with me, participated in the ceremony.

Before the ceremony, in the mathematics department lounge, our commencement speaker asked me if I was graduating. He said that I look very young, but I am more than a decade older than he is!

Friday, June 14, 2019

Hidden Giant Art in the Wilderness of Copenhagen

This hidden giant art (and its implementation) is so awesome!

(Tip of the cap to Christopher Dempsey.)

My 2011 D & D Character Sheet (According to my Students)

P.S. In case you are interested, here is my 2011 blog entry and the discussion therein.

A Colorful Visual Illusion

(Tip of the cap to Lucas Lacasa.)

Spot-On SMBC Comic about Scientific "Findings"

The comic-strip author this one.

Mouseover text: "Somewhere, there's a scientist reading this, wonder[ing] why I made a comic with no hyperbole."

Wednesday, June 12, 2019

Introductory Paragraph from a Book on Type Theory: A Wild Adventure

Now I want to start an actual scientific paper in this style. :P

(Tip of the cap to David Bindel.)

Tuesday, June 11, 2019

Tales from the ArXiv: "Bourgeois Functions"

The snippet below, from this new paper makes me wonder about a rigorous definition of a "bourgeois function"... 🤔

Sunday, June 09, 2019

20th Anniversary of Bobby Valentine's Dugout Disguise

Twenty years ago today, Bobby Valentine pulled his famous stunt. I remember watching this game on television.

It was awesome when Ichiro Suzuki paid homage to this incident last year.

Saturday, June 08, 2019


Very nice!

Friday, June 07, 2019

Amazing Sculptures from Tightly-Rolled Newspapers

These are incredible!

35th Anniversary of the Release of Tetris

Happy 35th anniversary, Tetris!

Thursday, June 06, 2019

Terry Tao's Guest-Starring Role in "Math With Bad Drawings"

P.S. Terry's reaction was amusing when I showed this to him. :)

Tuesday, June 04, 2019

A Yiddish Proverb with Mixed Feelings

Let's just say that I have mixed feelings about this proverb.

(Tip of the cap to Benjamin E. Hardisty.)

Sunday, June 02, 2019

Actual (Perhaps?) New Idea: Pogo Sticks Instead of E-Scooters

What could possibly go wrong?

Also: #nottheOnion

Update: One of my friends was suggesting that this is a joke from the 'company', and that may be true. There are so many real ridiculous things nowadays that I find it hard to tell.

A 1930s Pictorial Vision of the Future

Hey, look. Flying cars!

There are many cool things about this picture.

"Apostryphal Grammatical Constructions"

I think that "apostryphal" really ought to be a valid adjective. That seems like a great way to discuss apostrophes, especially when they annoy me or I want to change them.

Based on my quick googling, however, this appears to be apocryphal.

I also like the idea of evoking apocalypses in related comments and puns.

Example usage: "I rewrote the sentence to avoid apostryphal grammar."

Saturday, June 01, 2019

A Paper from Hell

It had to be done.

'Faces in Things' Twitter Account

This is glorious, of course.