Nathaniel Johnston @njohnston.ca · 25/08/2025Huge shout-out to authors who put humour, even very mild humour, in their papers. You keep me awake. 170
Nathaniel Johnston @njohnston.ca · 28/02/2025Now, two months later, Musk says that "Grok 3 is becoming superhuman" because Grok 3 obtained just as good as solution (i.e., an absolutely terrible non-solution) to this Putnam problem. Unreal. 030
Nathaniel Johnston @njohnston.ca · 01/01/2025Shameless self-promotion time: if you enjoyed this thread and/or are interested in these sorts of aspects of Conway's Game of Life, have a look at my (free) book "Conway's Game of Life: Mathematics and Construction", co-authored with Dave Greene: www.conwaylife.com/book/ 050
Nathaniel Johnston @njohnston.ca · 01/01/2025#3 (1/4): Oscillator density. In the early days of Life, it was conjectured that the maximum density (i.e., maximum ratio of alive cells to dead cells) of an infinitely large still life is 0.5. This density is easily attained by alternating rows of dead and alive cells. 130
Nathaniel Johnston @njohnston.ca · 01/01/2025#2 (1/4): Still life glider synthesis. A glider synthesis is a way of crashing together 2 or more gliders so as to create another object. For example, in the image below three gliders collide so as to create a lightweight spaceship. 130
Nathaniel Johnston @njohnston.ca · 01/01/2025#1 (1/4): Phoenices. A phoenix is an oscillator in which every cell dies in every generation (and thus every alive cell was dead in the previous generation, hence the name). The first known phoenix has period 2: conwaylife.com/wiki/Phoenix_1 130
Nathaniel Johnston @njohnston.ca · 20/12/2024But there's a problem: the answer was found by computing the thing for n = 1, n = 2, and n = 3, spotting a pattern, and hoping that the pattern continues. Seem familiar? 140
Nathaniel Johnston @njohnston.ca · 20/12/2024Wow, ChatGPT got the correct answer of 10^(n(n-1)/2)! People proclaim this would be scored 10/10 and that the AI apocalypse is here. 130
Nathaniel Johnston @njohnston.ca · 20/12/2024To see why this line of reasoning falls flat to me, let's look at its answer to this year's question A6. If you don't want to read the technical details of the question, all that really matters here is that the question asks you to compute a formula for something. 140
Nathaniel Johnston @njohnston.ca · 20/12/2024And the people reading the "proof" don't notice that it's garbage since they're exhausted from the previous five paragraphs which were almost entirely content-free and irrelevant (but technical and impressive-sounding!). 1110
Nathaniel Johnston @njohnston.ca · 20/12/2024This wouldn't be so annoying if ChatGPT were honest about how it came up with and verified (or didn't verify) the solution. But instead, it acts like a grade-grubbing student and throws some crap against the wall, hoping that something will stick. 1110
Nathaniel Johnston @njohnston.ca · 20/12/2024ChatGPT gets the right answer, which on the surface seems super impressive. But then you read its "proof" and see that it didn't actually prove anything: it just did a ton of computations, noticed a pattern, and hoped against hope that the pattern continues to hold forever. 2133
Nathaniel Johnston @njohnston.ca · 20/12/2024To illustrate what I mean by this, let's look at its answer to question B1, which asks for which sizes of grids it's possible to pick squares in a certain way. 130
Nathaniel Johnston @njohnston.ca · 20/12/2024ChatGPT, most of the time, simply does not prove its answer is correct. This isn't a matter of "lack of rigor" or however else people try to deflect this point. It's that ChatGPT quite simply ignores the entire crux of the given problem. 1110
Nathaniel Johnston @njohnston.ca · 20/12/2024The problem is that Putnam questions all require you to prove something. Not just compute it or get the right answer, but prove that it's right. Heck, lots of Putnam questions *tell* you the answer, and just want you to prove it correct. 190
Nathaniel Johnston @njohnston.ca · 20/12/2024First, the claims are that ChatGPT o1 scored 80+ points on the Putnam, or 60+ points, or high enough to be in the top 2% of participants, or whatever other impressive-sounding claim someone can make up. 141
Nathaniel Johnston @njohnston.ca · 20/12/2024There's been a bunch of claims (mostly on X) that ChatGPT did great on this year's Putnam math competition. Let's do a thread to talk about it! 🧵 #MathSky 24417
Nathaniel Johnston @njohnston.ca · 05/12/2024It looks like Overleaf's new AI writing tools don't like the notes that I make to myself while writing papers. 030
Nathaniel Johnston @njohnston.ca · 05/12/2024Had a recent research project where we had to evaluate this hideous sum. Convolution to the rescue! Made a video to talk about how it works (or at least how some similar but simpler sums work): www.youtube.com/watch?v=aIj6... 120
Nathaniel Johnston @njohnston.ca · 03/12/2024Me, a moron: I don't need a local TeX installation, Overleaf works so well and is so easy! Overleaf: like every online service that exists, goes down from time to time. Me: shocked Pikachu. 001
Nathaniel Johnston @njohnston.ca · 25/11/2024The On-Line Encyclopedia of Integer Sequences (OEIS) is hiring someone to manage the crazy number of sequences that it has to review. If you're a US resident with a math PhD, give it a look! Applications due Jan. 25, 2025. neilsloane.com/doc/OEIS.ME.... 02610
Nathaniel Johnston @njohnston.ca · 25/11/2024I wrote a review of Jane Hawkins' new book "The Mathematics of Cellular Automata", which is now online. tl;dr: It would be fun to teach a CA course from this book to students who have already taken Real Analysis. www.tandfonline.com/doi/full/10.... 020
Nathaniel Johnston @njohnston.ca · 22/11/2024Fun fact: my advanced linear algebra textbook has a page about exactly this! Screenshot attached. 160
Nathaniel Johnston @njohnston.ca · 18/11/2024When teaching multivariable functions, I've started using 3D prints of their graphs. In a lab this week, for example, students will have this 3D print in front of them and then have to sketch a contour plot based on it. 020