Mark Dominus

I'm an expert computer programmer, looking for work. Check out my résumé: https://plover.com/~mjd/cv/Mark%20Jason%20Dominus.pdf

Also, an amateur mathematician, but not the angle-trisecting kind.

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npub1hgcxucrw7vg0h709590mwsgfjvg0utpvn48nh87u4hsp68jq9rcqehqfuq

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mjd@mathstodon-xyz.mostr.pub

Profile Code

nprofile1qqst5vrwvph0xy8ml8j6zhahgyyexy879skf6nemnlw2mcqareqz3uqpz4mhxue69uhhyetvv9ujumt0wd68ytnsw43qvk92dd

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relay.mostr.pub

Author Public Key

npub1hgcxucrw7vg0h709590mwsgfjvg0utpvn48nh87u4hsp68jq9rcqehqfuq

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Last Notes

2026-10-30 17:59:24 UTC

Focusmate seems to have protanopia. The problem isn't in my camera, it's in software, because:
1. That background is a static image, not going through the camera, and in the original image I uploaded, the trees are normal autumn colors.
2. It only affects Focusmate, not any other web service like Google Meet or Zoom
3. When I test the camera locally, it's fine
My Focusmate partner sees everything miscolored, but I see them normally.
What could cause something like this?
https://media.mathstodon.xyz/media_attachments/files/117/531/141/140/823/695/original/847f11c4a28c65bb.png

2026-10-20 19:45:20 UTC

Claude just wowed me in a very mundane way. I wanted a custom icon to use in Notion, so I requested that Claude make me a 64×64 PNG”:
“a dark purplish-blue square with slightly rounded corners, and a white capital F inside.”
This it did, and I was 100% satisfied. (See the attached image.)
When I interrogated it about how it did that, it turned out it had written a Python program to draw the icon, using the “Pillow” library.
Here's the part for the program that draws the white "F":
d.rectangle([x0, y0, x0 + t, y1], fill=white) # stem
d.rectangle([x0, y0, x1, y0 + t], fill=white) # top bar
d.rectangle([x0, 29 * S - t // 2 + S, 42 * S, 29 * S + t // 2 + S], fill=white) # middle bar
It didn't use Pillow's text-drawing feature, it built the F out of rectangles. When I asked why, it said:
“I didn’t check whether the sandbox had any fonts installed, and I didn’t want the script to fail on a missing font file. Drawing the F from rectangles has no external dependency, so it works on any machine with Pillow.”
You can't trust anything Claude says about what it was thinking, but this is a really plausible answer, and I believe it is probably correct.
https://media.mathstodon.xyz/media_attachments/files/117/474/939/122/259/326/original/35b4b03c57136d1e.png

2026-10-18 21:24:10 UTC

“Between 2011 and 2025, Ghana has seen a 98% drop in malaria fatalities, and Dr Nana Yaw Peprah, Deputy Head of the National Malaria Eradication Programme, says elimination is ‘within reach’.” 52 Malaria deaths in 2025.
#shareGoodNewsToo
https://www.gavi.org/vaccineswork/ghana-path-eliminating-malaria

2026-10-14 14:39:59 UTC

A unit circle (blue curve) satisfies the equation \[ x^2 + y^2 = 1\] but if instead of the Euclidean norm you use the p-norm, you have the equation \[ {|x|}^p + {|y|}^p = 1.\]
When p=1 you get what's called the "Manhattan" metric, and the "circles" are diamond-shaped (red curve); as p goes to infinity the "circles" become more and more nearly square, and are called "squircles" (green and purple curves).
Today I learned that if one generalizes trigonometry to squircles, it's called "squigonometry" and the x and y coordinates of points on the squircle are given by the squine and cosquine functions.
https://en.wikipedia.org/wiki/Squigonometry
https://media.mathstodon.xyz/media_attachments/files/117/439/771/538/788/736/original/156894e98223e911.png

2026-09-24 14:54:40 UTC

I'm looking for work, please boost!
I'm a software engineer with 35 years of experience. I've worked across an unusually wide range of domains: mobile game backends, privacy-preserving data platforms, high-throughput COVID testing infrastructure, email and account systems, e-payment processing, job marketplace systems, and bioinformatics. I pick up new domains quickly and have a history of doing it repeatedly. I understand how to turn business needs into engineering requirements.
I prefer to work remotely but I am open to an in-office job in the Philadelphia area or especially in Philadelphia itself. I've often worked remotely since the 1990s and can operate with minimal supervision. Several of my favorite projects were self-directed: I identified the need, built the thing, and shipped it. My preferred time zone is America/New_York, but I'm flexible
Some of the many, many technologies I've used are: Python, Perl, TypeScript/JavaScript, Haskell, Go, C, Java. Postgres, MySQL, SQLite. Flask, SQLAlchemy. AWS (Lambda, S3, RDS, SQS, EC2). Docker, Git. Github and Gitlab.
I've also repeatedly picked up new languages and stacks as needed: Haskell for differential privacy research, TypeScript for a 24/7 AWS Lambda system, Flask for my most recent employer. I've become productive with new systems over and over, and I can do it quickly.
I'm published author (Higher-Order Perl, Morgan Kaufmann), longtime blogger, and conference speaker with a reputation for making complex ideas clear.
I am a U.S. citizen.
My résumé is at https://
plover.com/~mjd/cv/Mark%20Jason%20Dominus.pdf
mjd@pobox.com
Thanks!
#OpenToWork #remoteWork #softwareEngineering #Python #backend #hiring
#fediHire
#getFediHired

2026-09-04 15:38:59 UTC

“I think we don't actually get to make a choice between an incoherent mess of composable paraphernalia and a coherent, well-designed but noncompositional system. Rather, we get a choice between a incoherent but useful mess and an incomplete, limited noncompositional system.”
(Me, discussing Unix, but also thinking of Git and many other examples.)
https://blog.plover.com/Unix/tools.html

2026-08-21 08:55:26 UTC

It's 1986. You've built a limited but working time machine. Each week, it sends back a message from the future: a single news headline from the year 2026.
You arrange a meeting with a billionaire who might be able to help you exploit your source of future information. She is skeptical, but you ask her to be patient while the machine locks onto the signal from 2026. First there is the blue glow of Cherenkov radiation, then a brief burst of rhythmic buzzing as a perforated iridium ribbon of emerges from the slot. The billionaire is impressed.
You carefully insert the end of the silvery ribbon into a second device that will decode the perforations. There is a rythmic clicking sound as the little switches are depressed, or not, by the ribbon. You realize you're holding your breath. What will it say? Will it report a scientific breakthrough? A natura disaster? A war?
But as the billionaire watches the CRT screen her expression is first puzzlement, then disappointment, then disgust. Without a word she rises from the chair and walks out.
You dive into the chair and look at what is on the screen.
https://www.theguardian.com/world/2026/aug/21/python-jodie-foster-snake-cancer-electrochemotherapy

2026-08-19 17:56:29 UTC

1. Notice that there is only a little coffee left in my large mug
2. Turn on the electric kettle
3. Put three spoonfuls of coffee powder in the cup
4. Kettle boils
6. Drink coffee from cup
7. Realize I missed a very important step 5.

2026-08-16 12:45:01 UTC

“Silicon Valley will spend millions developing a glove that translates sign language into speech (badly), but they won't spend ten minutes adding Alt-Text to their images.”
(Robert Kingett)
https://sightlessscribbles.com/posts/disability-dongle/

2026-08-13 18:44:38 UTC

- reply

@nprofile…tkx6 Maybe so! I used to have a paypal link on the page, and I got occasional donations, but I decided I didn't like doing it. (Also, Paypal, ugh.)
I do like your suggestion though. And if nothing else I would enjoy donating the money to charity.
Thanks for the suggestion.

2026-08-13 16:36:16 UTC

People have asked me a couple of times why I don't try to “monetize” my blog. That would be completely daft. The blog is one of my great delights in life. I write it because I like to write and because I hope other people will read it. Why would I subject myself to a lot of horrible advertising and promotion and business administration, that would leave me with less energy for writing, and would shut out readers who want to listen to what I have to say (paywalls), just to make what would probably be an insignificant amount of money?
In the “best” case the blog would be such a success that I'd be able to quit my job and do it full-time. On a schedule. With people yelling at me all the time about how I wasn't writing what they wanted to hear. If when I die I have to atone in Purgatory for my sins, I imagine that's how I'll have to do it.
The idea of having an LLM write for me seems similar. “But it would make you more productive!” Maybe, but it would make me more productive of something that wasn't worth producing.
It's been observed many times that many more people want to have published a book than actually want to _write_ a book. These people sometimes approach writers and say “I have a great idea for a book! All you have to do is write it!” I bear these people no ill will and I'm even a little bit happy for them if LLMs make it possible for them to get the books they wanted.
But I'm not going to do it, I'm going to keep writing because I'm a writer and I like to write.
Thanks to those of you who sometimes join me on my writing journey.
https://blog.plover.com/
#writing #blogging

2026-08-13 12:34:24 UTC

Thanks, I'd rather eat my own kneecaps.
https://media.mathstodon.xyz/media_attachments/files/117/088/214/452/422/503/original/3d8d6fdb8da97133.png

2026-08-06 23:06:05 UTC

Ugggh.
% jobs
[1] Stopped emacs -nw book/elbow-shelf.blog
[2] Stopped emacs -nw book/elbow-shelf.blog
[3] Stopped emacs -nw book/elbow-shelf.blog
[5] Stopped emacs -nw math/ordinals/04-coordinates.blog
[6]- Stopped emacs -nw math/egyptian-multiplication.blog
[7]+ Stopped emacs -nw math/egyptian-multiplication.blog

2026-07-31 13:51:47 UTC

Polychaetes are easily confused with parakeets but are by no means interchangeable with them and are not even closely related.

2026-07-31 12:27:45 UTC

“Who to Trust, Google or the Russian Ministry of Defense? In 2015, that was a rhetorical question. Not anymore.”
(Henk van Ess)
https://www.digitaldigging.org/p/how-to-plant-a-nuclear-plant-in-iran

2026-07-23 16:15:39 UTC

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@nprofile…4fj5 Bonus trivia: It is a coincidence that the names "wombat" and "numbat" sound similar. They are from unrelated languages spoken on opposite sides of Australia.

2026-07-19 13:30:39 UTC

Roche is no longer updating their famous "biochemical pathways" poster or selling physical copies, but you can still download a PDF and manufacture one yourself. Or just admire it on the screen.
Here's a screencap of a small but crucial part, the citric acid cycle. (Glucose enters from the left, but I cropped it out.)
https://www.biochemical-pathways.org/
https://media.mathstodon.xyz/media_attachments/files/116/946/869/916/372/139/original/5da0160c85fff79b.png

2026-07-19 00:41:20 UTC

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@nprofile…m8u8 Why is the water use is not consequential if the plant is properly sited?
(This is a real question, not an attempt to argue.)

2026-07-18 19:43:59 UTC

The patron saint of computer programmers is St. Isidore of Seville,who “helped to standardise the use of the full stop, comma and colon.”.
https://en.wikipedia.org/wiki/Isidore_of_Seville

2026-07-18 19:31:34 UTC

“I can never remember if it was Sun Tzu or Clausewitz who cautioned not to back your enemy into a corner from which the only way out is over your own corpse, but that is precisely what the tech bros did to nation-states with encryption, and now the nation-states are making their way out of that corner.”
(Poul-Henning Kamp)
https://queue.acm.org/detail.cfm?id=3818307

2026-07-09 13:04:29 UTC

The Ferengi First Law of Acquisition is “once you have their money, you never give it back”.
But they don't seem to acknowledge what I, as a long time consultant, would have cited as the First Law: “when someone offers to give you money, say yes.”

2026-07-08 14:13:39 UTC

- reply

@nprofile…tkx6 But at the time I saw that picture of Mac Lane, Paul was only 45.
I hope I still look as good as Paul when I'm 87. He's certainly aged a lot better than John.

2026-07-08 13:50:22 UTC

As a very young man, seeing these two pictures side by side made a deep impression on me. It was the first time I really understood that this was going to happen to me too.
(Both pictures are Saunders Mac Lane.)
https://media.mathstodon.xyz/media_attachments/files/116/884/658/797/944/716/original/105323e76266ff68.png
https://media.mathstodon.xyz/media_attachments/files/116/884/660/650/808/120/original/67cac1bd5d56db35.png

2026-07-01 20:20:56 UTC

Here's one reason why birthright citizenship is important in the USA.
Suppose my citizenship is questioned. Mine specifically, I mean. The government wants to deport me, detain me without trial, take away my voting rights, or prosecute me for being in the country illegally.
I have an easy answer to this. I produce my birth certificate, which says that I was born in New York State in 1969. They confirm this with the New York State Department of Health, and that is the end of the matter.
Without birthright citizenzship, with the regime that Alito and Gorsuch want, it's *not* the end of the matter. The government can look at my birth certificate, scoff, and demand that I prove my parents were here legally. And they can imprison me until then.
Okay, but I can prove that they were here legally. After all, they were citizens from birth. I produce my parents’ birth certificates, showing that they were born in New York State in 1939 and 1943 respectively. Do you see where this is going?
But that's not good enough because without birthright citizenship, just being born in the USA is not good enough. I also have to prove that my grandparents weren't here illegally.
And proving that my grandparents were U.S. citizens is not good enough. In fact my paternal grandfather was brought here as a child, 1913. Can I prove he was here legally? Perhaps his immigration paperwork contains a misstatement of fact, his naturalization was void all along, my father has been here illegally for 87 years, and I am subject to immediate deportation to Hungary or El Salvador or South Sudan.
Without birthright citizenship, every person's status is in precarious.

2026-07-01 15:27:35 UTC

UK petitions web site summarily rejects petition asking them to stop rejecting every petition.
https://petition.parliament.uk/petitions/771707
https://media.mathstodon.xyz/media_attachments/files/116/845/409/199/691/340/original/c1dd64a9734ee9ab.png

2026-06-30 03:42:32 UTC

Best Hacker News comment in a while:
“Homeopathic medicine is already recommended by 1 out of 1000000000000000000 doctors.”

2026-06-29 12:34:44 UTC

This is the most exciting technical thing I've seen this week. Stephen Diehl has built an algebraic effects language, #prism , that might actually be usable.
I've been excited about algebraic effects since Bauer and Pretnar's 2012 paper. Haskell's stacks of monad transformers always looked to me like a first-generation hack: yes, we have the technology that could fix the Awkward Squad, but we don't know yet what to do with it. Algebraic effects seemed like they could be the way forward.
But I tried programming in Eff and found it impossible to make _anything_ work.
Even if Prism isn't practical for practical programming, it's a big step forward, and worth a look just for the ideas.
#haskell #algebraicEffects #programmingLanguages
https://www.stephendiehl.com/posts/prism/

2026-06-25 16:29:50 UTC

“Vladimir Putin signed Federal Law 139-FZ on July 28, 2012, an amendment to the statute on protecting children from harmful information, child abuse imagery, drugs, suicide methods. It created a single national registry of blocked sites under Roskomnadzor, in force that November. By the end of 2013 the Lugovoi law had bolted extrajudicial blocking for extremism and calls to protest onto the same registry, and by 2022 it was the instrument shutting down independent outlets and war coverage. The children were the door the apparatus walked through.”
“The democracies are building the same lever with better manners.”
(Denis Stetskov)
https://techtrenches.dev/p/the-cost-of-reading-everyone-just
#surveillance #thinkOfTheChildren

2026-06-25 16:24:15 UTC

“For most of history, surveillance ran into the same wall: payroll. A Soviet censor could open your letter. He could not open everyone’s letter, because steaming envelopes takes hands and there were never enough hands. The Stasi got closest, running files on a share of the East German population large enough that historians still argue the exact fraction, and it took warehouses of paper and a network of informants the size of an army to do it. The ceiling was human. Reading you cost a person a day, and a person’s day costs money.”
“What protected the ordinary person was the price of attention. You were boring, and boring was expensive to read.”
“AI removed the ceiling. A model reads every message at a cost rounding to zero, sorts them, flags the interesting ones, and never asks for a raise. The thing that made mass reading impossible was arithmetic, and the arithmetic just inverted. Two variables remain: who holds the data, and what they say when the state asks.”
(Denis Stetskov)
https://techtrenches.dev/p/the-cost-of-reading-everyone-just
#ai #surveillance

2026-06-17 21:45:18 UTC

“Mangrove forests are healing after decades of human destruction”
“Since 2010 the world has been gaining more mangroves than it has been losing—driven by stronger legal protections and increased public awareness of their importance.”
#shareGoodNewsToo
https://www.bbc.com/news/articles/cn4pk07npvvo

2026-06-17 15:19:29 UTC

- reply

@nprofile…tkx6 Sure, but that one is well-known.
Also “flammable” is a more recent coinage introduced specifically to avoid the confusion of “inflammable”. I don't think “heritable” is analogous.

2026-06-17 15:09:22 UTC

“Inheritable” is not the opposite of “heritable”.

2026-06-15 16:33:08 UTC

I'm looking for work, please boost!
I'm a senior software engineer with 35 years of experience. I've worked across an unusually wide range of domains: mobile game backends, privacy-preserving data platforms, high-throughput COVID testing infrastructure, email and account systems, e-payment processing, job marketplace systems, and bioinformatics. I pick up new domains quickly and have a track record of doing it repeatedly. I understand how to turn business needs into engineering requirements.
I've worked remotely since the 1990s and can operate with minimal supervision. I don't need hand-holding to find the right problem to solve. Several of my most valued projects were self-directed: I identified the need, built the thing, and shipped it.
Some of the technologies I'm familiar with include: Python, Perl, TypeScript/JavaScript, Haskell, Go, C, Java. Postgres, MySQL, SQLite. Flask, SQLAlchemy. AWS (Lambda, S3, RDS, SQS, EC2). Docker, Git. Github and Gitlab.
I've also repeatedly picked up new languages and stacks as needed: Haskell for differential privacy research, TypeScript for a 24/7 AWS Lambda system, Flask for my most recent employer. I've become productive with new systems over and over, and I can do it quickly.
I'm also a published author (Higher-Order Perl, Morgan Kaufmann), longtime blogger, and conference speaker with a reputation for making complex ideas clear.
My résumé is at https://plover.com/~mjd/cv/Mark%20Jason%20Dominus.pdf
mjd@pobox.com
Thanks for your attention!
#OpenToWork #remoteWork #softwareEngineering #Python #backend #hiring
#fediHire #getFediHired

2026-06-15 03:07:20 UTC

- reply

@nprofile…gwnq 😢
https://media.mathstodon.xyz/media_attachments/files/116/751/913/504/217/667/original/1869fd738cdd61c5.png

2026-06-14 19:48:11 UTC

@nprofile…saqv The segmented displays on the Philadelphia L line are different from all of these. Would you like me to go take photos?
https://aresluna.org/segmented-type/

2026-06-10 15:56:53 UTC

I'm really interested to see how much of Paul Halmos' advice on "how to study" is things I discovered on my own. The main thing is that one _must_ read actively, and focus one's attention. Much of Halmos' advice is techniques for doing this. For example:
“Another way I keep active as I read is by changing the notation; if there is nothing else I can do, I can at least change (improve?) the choice of letters. Some of my friends think that’s silly, but it works for me.”
I think it's an unfortunate omission that Halmos doesn't say explicitly that reading should be done with a pencil and a pile of paper at hand. The "change the letters" above hints at this.
An important technique I think he leaves out is to take notes while you read! I'll read a sentence, then write about it, write my thoughts, my questions. If I don't have any thoughts or questions, I'll write down the sentence in my own words, and if I don't have that then I'll just write down the sentence verbatim. I often find that while I'm writing some thoughts and questions occur to me. If not, maybe I should take a break. Thinking and learning is hard work.
This is why we take notes in lectures, why making a recording is not good enough. As Halmos says, the purpose of the notes is to focus your attention on the material.

2026-06-07 00:47:03 UTC

Does it sometimes happen to people that they have been using Google Auth everywhere, and then one day Google revokes their account and refuses to vouch for them, and they're locked out of everything?
I'm not just being paranoid, am I? I'll be happy to hear it if this never happens.

2026-06-01 21:27:25 UTC

Phrases you don't want to hear the judge use when mentioning your witnesses:
“The Court has considered their testimony, to the extent that it is credible.”
(USA v Abrego, 3:25-cr-00115,Tennessee Middle District)
https://storage.courtlistener.com/recap/gov.uscourts.tnmd.104622/gov.uscourts.tnmd.104622.312.0.pdf

2026-05-08 14:13:14 UTC

Wishing you all a cheerful and optimistic Victory Over Fascism Day!
https://en.wikipedia.org/wiki/Victory_in_Europe_Day

2026-05-06 14:30:40 UTC

Octopus neurology just gets crazier and crazier.
Note that the diagram is a little misleading. An octopus does not have a north arm and a south arm as shown here. It has four arms on the left, and four on the right.
So here we see that the frontmost of the left arms is directly connected to the rearmost of the left arms, but this connection bypasses the other two left arms. It is, however, connected directly with the third arm back on the right.
Source: https://doi.org/10.1016/j.cub.2022.11.007
#octopus #wtf
https://media.mathstodon.xyz/media_attachments/files/116/528/087/356/405/523/original/4d54b5be79957187.png

2026-05-05 21:40:22 UTC

“There's a recent report of a method to make a more stable form of [this substance], by mixing it with TNT.”
#nevent1q…y2f7

2026-05-03 18:30:28 UTC

#dodecahedron #dodecahedronDimanche
https://media.mathstodon.xyz/media_attachments/files/116/512/055/025/471/253/original/d9f03b744a6de2bc.jpeg

2026-05-01 12:24:30 UTC

A COMPUTER CANNOT FIND OUT
THEREFORE A COMPUTER MUST NEVER BE ALLOWED TO FUCK AROUND

2026-04-28 16:32:53 UTC

- reply

@nprofile…d98r My kid pointed out that our holly tree has eyes, and now I can't unsee it.
https://media.mathstodon.xyz/media_attachments/files/116/483/290/439/581/853/original/5266789c98338f7a.jpg
https://media.mathstodon.xyz/media_attachments/files/116/483/290/448/507/334/original/d0ad8a7cb37c08d5.jpg

2026-04-27 17:36:52 UTC

- reply

@nprofile…tfwq This is a different sort, and it's notorious. https://oeis.org/A000053

2026-04-17 04:10:52 UTC

“If you can’t do your job without having to regularly excuse sloppiness on the grounds that you have no incentive to be less sloppy, at least have the decency not to say that out loud in a crowded room or Twitter feed full of people who indirectly pay your salary.”
https://talyarkoni.org/blog/2018/10/02/no-its-not-the-incentives-its-you/

2026-04-06 13:28:17 UTC

Initially surprising math fact that is not at all hard to prove: For every number n, there is some multiple of n whose digits have the pattern 111…000….
For example:
1×1 = 1
2×5 = 10
3×37 = 111
4×25 = 100
5×2 = 10
Hmm, those were not very interesting. Let's try:
31 × 3584229390681 = 111111111111111
32 × 3125 = 100000
33 × 3367 = 111111
34 × 326797385620915 = 11111111111111110
35 × 31746 = 1111110
36 × 308641975 = 11111111100
37 × 3 = 111
38 × 29239766081871345 = 1111111111111111110
Bonus fact: The same is true of the base k digits.

2026-04-05 15:12:40 UTC

“You don’t have to have poor quality software just because you’re using AI for coding. That is my hot take for today. People have bad quality software because they decide to have bad quality software.”
https://bramcohen.com/p/the-cult-of-vibe-coding-is-insane
Cohen's description of his work process with AI sounds very similar to the one I have developed: a discussion of what I want to do, how, and why, followed by the AI one-shotting the actual task.

2026-04-03 22:13:54 UTC

Citizens of the fediverse, send those answers to me instead!
#nevent1q…05q4

2026-03-25 01:19:05 UTC

The town of Neunkirchen is not so named because it contains nine churches. I have not been so disappointed by German since I learned that Furtwängler was not an occupational name for someone who furtwangles.

2026-03-24 14:31:42 UTC

One fun thing about #textureTuesday is that the barrier to entry is so low. Interesting texture is literally everywhere.
https://media.mathstodon.xyz/media_attachments/files/116/284/621/912/438/212/original/c19170610de54822.jpg
https://media.mathstodon.xyz/media_attachments/files/116/284/621/912/401/226/original/d6b5517e8bbd39ef.jpg

2026-03-24 10:52:31 UTC

It's 1986. You've built a limited but working time machine. Every week, it materializes a small slip of paper with a news headline from 2026.
You arrange a meeting with a millionaire who might be able to help you exploit your source of future information. She looks skeptical, but you ask her to be patient while you warm up the machine. Presently, a bit of paper materializes from nowhere. The millionaire is impressed.
You hand her the slip, wondering what wisdom it will impart. The outcome of a major sporting event? An election result? The name of a successful company that doesn't yet exist?
But the millionaire's expression changes to a scowl. She lets the slip flutter to the floor as she leaves your apartment without another word.
You retrieve the slip and read the headline that your machine has produced.
https://www.nytimes.com/athletic/7142152/2026/03/23/cornhole-player-amputee-arrested-murder-dayton-webber/

2026-03-09 22:21:14 UTC

How many ways are there to tile a 2×2n rectangle with n Tetris tiles?
The answer turns out to be the square of the n'th #Fibonacci number: 1, 1, 4, 9, 25, 64, 169, …
https://shreevatsa.net/post/tetris-tilings-fibonacci/ by @nprofile…sphc
https://media.mathstodon.xyz/media_attachments/files/116/201/590/949/092/640/original/fb0d461b91c19e04.png

2026-03-09 17:36:34 UTC

“Ireland shuts last coal plant, becomes 15th coal-free country in Europe”
#shareGoodNewsToo
https://www.pv-magazine.com/2025/06/20/ireland-coal-free-ends-coal-power-generation-moneypoint/

2026-03-03 20:47:32 UTC

“Shock! Shock! I learned yesterday that an open problem I’d been working on for several weeks had just been solved by Claude Opus 4.6… It seems that I’ll have to revise my opinions about “generative AI” one of these days. What a joy it is to learn not only that my conjecture has a nice solution but also to celebrate this dramatic advance in automatic deduction and creative problem solving.”
(Donald E. Knuth)
https://www-cs-faculty.stanford.edu/~knuth/papers/claude-cycles.pdf

2026-02-28 14:46:33 UTC

It's a theorem that while addition can be done by a finite-state machine, the amount of memory required for multiplication can't be bounded in advance.
Any actual computer, though, has a bounded amount of memory: 2¹⁶ bits or whatever.
Therefore, computers can't perform multiplication of numbers. This is mathematical and engineering reality. People who claim they do are confused, deceived, or merely ignorant.

2026-02-26 08:24:37 UTC

“Breakfast is a vector space. You can place pancakes, crepes, and scrambled eggs on a simplex where the variables are the ratios between milk, eggs, and flour. We have explored too little of this manifold. More breakfasts can exist than we have known.”
https://moultano.wordpress.com/2026/02/22/the-hunt-for-dark-breakfast/

2026-02-21 18:29:14 UTC

“Most electronic shopping cart wheels listen for a 7.8 kHz signal from an underground wire to know when to lock and unlock. A management remote can send a different signal at 7.8 kHz to the wheel to unlock it. Since 7.8 kHz is in the audio range, you can use the parasitic EMF from your phone's speaker to ‘transmit’ a similar code by playing a crafted audio file.”
This sounds improbable but I needed to use it just now and it worked both times.
https://www.begaydocrime.com/

2026-02-13 16:03:00 UTC

@nprofile…gu9p I'm so sorry I forgot our meeting! Can we schedule a different one!

2026-02-12 16:48:01 UTC

There are exactly 18 ways to partition the integer 13 into 4 parts, and also 18 ways to partition it into 5 parts.
Is there an identifiable structural reason for this, or is it just a coincidence?
I have put a small bounty on my 2013 Math SE question about it.
https://math.stackexchange.com/q/620987/25554

2026-02-11 17:04:34 UTC

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@nprofile…33pr Statutory law actually forbids advertising on Interstate highways, _except_ on special standardized blue amenity signs and under a few very specific circumstances.
Having driven in Europe, I like ours much better. In Europe nontextual signs are important because of the wide variety of different languages.
Regarding some of the odd exceptions to the no-advertising rule, see https://blog.plover.com/law/free-coffee.html

2026-02-11 16:42:52 UTC

I was skimming through the Manual on Uniform Traffic Control Devices yesterday, and thinking, as I often do, that one of the finest things in the U.S. is our highway signage. No joke, I am really proud of our achievements here. They are a triumph of civic administration and a valuable application of our affluence for the public good.
(The manual is available online for free and will be of great delight to many varieties of nerd: https://mutcd.fhwa.dot.gov/kno_11th_Edition.htm )
And then I thought it's probably only a matter of time until the current administration figures out a way to line their pockets with highway sign funds, announces that highway signs are Fake News and Woke and fucks them up somehow or eliminates them entirely.
https://media.mathstodon.xyz/media_attachments/files/116/052/990/000/172/406/original/75921a9bac21279c.png

2026-02-10 17:45:49 UTC

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@nprofile…vhdw They're new to me, so thanks!

2026-02-07 13:55:46 UTC

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@nprofile…vhdw Looked it up, I've heard of the person but not enough to know his work.
He's very easy on the eyes though. It's a long shot but does he also happen to moonlight as a pinup calendar model?

2026-02-07 13:52:46 UTC

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@nprofile…vhdw Persi Diaconis? No, he's too old. From the name I want to say D.J. Bernstein but he's about the last person I would expect. Ron Graham is dead.
I give up.

2026-02-05 20:43:33 UTC

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@nprofile…t6k2 The fuel economy is also about 7% worse at 70 mph. Air resistance scales quadratically with velocity.
https://www.energy.gov/eere/vehicles/fact-982-june-19-2017-slow-down-save-fuel-fuel-economy-decreases-about-14-when

2026-02-05 20:02:46 UTC

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@nprofile…t6k2 I often think about this when I'm driving the car. Driving at 70 mph instead of 65 cuts a 120-minute trip to no less than 111 minutes. But it increases the risk of a crash by much more—the kinetic energy alone is 15% higher.

2026-02-05 16:59:44 UTC

Human guinea worm cases down from 3,500,000 to 10 (yes, ten) between 1986 and 2025.
https://arstechnica.com/health/2026/02/guinea-worm-on-track-to-be-2nd-eradicated-human-disease-only-10-cases-in-2025/
#shareGoodNewsToo

2026-02-03 19:52:26 UTC

UK Government publishes landmark Animal Welfare Strategy, plans to introduce:
* A ban on cages for hens
* A ban on cages for mother pigs
* A shift away from ‘faster-growing’ chickens and male chick killing
* Phasing out CO2 stunning of pigs
* Slaughter protections for farmed fish
https://animalequality.org.uk/news/2025/12/22/uk-government-publishes-landmark-animal-welfare-strategy/
#shareGoodNewsToo

2026-01-30 19:53:24 UTC

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@nprofile…t6k2 I feel it's about telling the truth about what our capabilities are, rather than pretending that we can perform superhuman tasks.

2026-01-29 19:42:00 UTC

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@nprofile…vhdw @nprofile…7jv6 That's a much better answer than I was expecting, which was more like “the polytope afficionados call this a nonagonal ortho-procrustulated histopyramid.”

2026-01-23 13:39:24 UTC

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@nprofile…nsl7
https://media.mathstodon.xyz/media_attachments/files/115/944/686/250/812/135/original/3ea49ac68a0009c9.png

2026-01-20 19:52:56 UTC

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@nprofile…vhdw There is a crucial word missing from ¶2, maybe "vertex"?

2026-01-19 17:30:56 UTC

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@nprofile…g0zc I've never been clear on whether Irish is hard for me to understand because the spelling is inconsistent, or if only because the spelling is so unlike English. I thought it was probably the latter. Is that incorrect?

2026-01-19 14:07:53 UTC

What languages, like English, have a script in which symbols represent sounds, but also (like English) represent it so poorly that the reader often can't know from the spelling how the word is pronounced?

2026-01-16 22:19:34 UTC

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@nprofile…t6k2 I honestly thought there was no way he could make himself more of a pathetic loser.

2026-01-14 16:12:25 UTC

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@nprofile…dn5h The solution was right in front of us all the time!

2026-01-14 12:48:06 UTC

Some languages don't have enough commitment to backward compatibility, some have too much.
Why can't anyone take the obvious, sensible middle ground of breaking only the features I find stupid and useless and keeping the ones on which my code depends?

2026-01-13 19:40:09 UTC

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@nprofile…dxrd What prevents one from perturbing the vertices to points with rational coordinates by sufficiently small amounts that the topology is unaffected?

2026-01-09 18:29:55 UTC

“In the play [Peter Pan], it is implied that Hook attended Eton College and Balliol College, Oxford, and his final words are ‘Floreat Etona’, Eton's motto.”

2026-01-09 14:00:28 UTC

One of the cooler things I saw in the Corning Museum of Glass was this chandelier made of blue glass butterflies. The butterflies are actually made of recycled solar cell material, and they're wired up so that the chandelier lights up with no external power source, the power is supplied by the butterflies themselves.
https://glasscollection.cmog.org/objects/58287/virtue-of-blue
#CMoG
https://media.mathstodon.xyz/media_attachments/files/115/865/480/974/023/923/original/c0d24346155aba83.png
https://media.mathstodon.xyz/media_attachments/files/115/865/481/372/384/510/original/09fd983f5b25fc99.png
https://media.mathstodon.xyz/media_attachments/files/115/865/481/846/191/900/original/37e6e34e7fa47bc0.png

2026-01-03 15:22:11 UTC

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@nprofile…vhdw @nprofile…eljp If they had done that, a programmer who tried setting a flag variable to true with `flag =1` would have inevitably gotten subtle bugs far away. It would have been an obvious footgun.

2026-01-03 15:13:39 UTC

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@nprofile…vhdw @nprofile…eljp Because C's 'if' uses zero for false and nonzero for true, and bitwise negation wouldn't work because ~true could evaluate to true.

2026-01-03 14:30:21 UTC

Why are there two notations for logical negation?
∼ was originally a stylized letter "N" for "not".
¬ is a vestigial version of the notation of Gttlob Frege's “Begriffsschrift”. In that notation, proofs were represented as formulas connected with lines, showing implications. To negate a formula, Frege decorated its line with a little hanging tick mark. Begriffsschrift wasn't successful, but some of its notation lingers.
https://en.wikipedia.org/wiki/Begriffsschrift
----- Others
Sometimes a minus sign was used, to analogize logical quantities to numeric ones: Logical negation is supposedly like arithmetic negation. I think this was originally due to Boole. But it doesn't work well. If you want 0 to be false and ` to be true, then you have to accept -X as an abbreviation for 1-X. If you want 0 to be false and nonzero to be true, it doesn't work at all, since then ‑false = false and ‑true=true. If you make true 1 and false ‑1, it works, but then logical and is no longer multiplication. Again, so elegant! But wrong.
Sometimes a vinculum (overbar) is used to negate a formula. This works nicely for short formulas such as atoms, but becomes unwieldy, as vinculums usually do.
Programming languages often use `!`. I'm not sure which was first to do this. C, perhaps? I think the idea was that the opposite of == is !=, to suggest the slash in ≠, and then if you omit the = part you are left with the ! to mean negation.
The Algol 60 report uses the symbol ¬, but in actual code had `NOT`. Fortran, of course, used `.NOT.`.The dots tell you that it is an operator rather than a variable named NOT. Reserved keywords had not yet been invented.

2025-12-28 15:33:13 UTC

Lately I've been puzzling about the confusingly abstract English word “condition”, trying to think how I would explain it to an English language learning person.
1. I will go with you, on one condition:…
2. What condition is your car in?
3. Air conditioner
4. Conditional statements
5. ??
I haven't found a challenge this hard since “even”.

2025-12-28 14:16:12 UTC

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@nprofile…rrqe “You taught me language, and my profit on 't / Is I know how to curse.” (_The Tempest_)

2025-12-28 14:15:28 UTC

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@nprofile…fhty That's a good argument that the claimed effect is real, thanks!

2025-12-28 05:13:32 UTC

“A Fibonacci Sequence in Rib Number for a Barrel Cactus” (Robberecht and Nobel, Ann. Bot. 51 p.153–155 (1982)) says:
“Fibonacci numbers of ribs in _F. acanthodes_ are clearly illustrated in Fig. 1(a), where individuals with rib numbers of 5, 8, 13, or 21 comprised 56 per cent of those surveyed. An additional 19 per cent had rib numbers within 1 of a Fibonacci number.”
Counts of the number of individuals with each number of ribs are not available to me.
Suppose rib numbers are distributed in some plausible way, maybe hyperbolically, starting with 2 or 3. How surprising is it that 56% have 5, 8, 13, or 21 ribs, or that 75% have 4, 5, 6, 7, 8, 9, 12, 13, 14, 20, 21, or 22 ribs? That excludes only 10, 11, and 15–19. Isn't this reasonably likely even if the number of ribs does _not_ tend to favor Fibonacci numbers?
(Morphological and developmental evidence does tend to confirm the hypothesis.)
https://www.jstor.org/stable/42764193

2025-12-22 12:49:31 UTC

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@nprofile…rrqe The framing of this as “pink” seems to make explicit that the whole thing was based on sexism and contempt for women scholars, right from the outset.

2025-12-20 13:06:06 UTC

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@nprofile…5w9a
I once read a story about the people writing the software for the NASA Apollo missions. There was a functionary in charge of weight accounting, who came to them and asked how much the software would weigh.
They told him it weighted nothing, but the functionary had heard *that* one before and insisted—everything had to be accounted down to the last ounce. He demanded to see it.
They showed him a stack of punched cards, and he was triumphant. “You see,” he said smugly, “it doesn't weigh only ‘nothing’!”
“No, you misunderstand,” they replied. “The cards aren't going on the spacecraft. Only the holes.”

2025-12-19 18:58:46 UTC

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@nprofile…l4xy Sort of both? I learned about it from a note in the front matter of my copy of the book it was in, _The Canterbury Puzzles_. It had been added there in the Dover edition.

2025-12-19 18:55:59 UTC

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It's a spoiler just to mention the available denominations of British coins of the time, but here they are:
¼d, ½d, 1d, 2d, 3d, 6d
1s, 2s, 2s6d, 4s, 5s, 10s
And 1s = 12d. The coins in the diagram are 5s and 2s respectively.

2025-12-19 18:52:30 UTC

As a kid I loved this puzzle by H.E. Dudeney:
“Place the fewest possible current English coins in the seven empty divisions, so that each of the three columns, three rows, and two diagonals shall add up fifteen shillings. Of course, no division may be without at least one coin, and no two divisions may contain the same value."
"But how can the coins affect the question?" asked Grigsby.
"That you will find out when you approach the solution."
"I shall do it with numbers first," said Hawkhurst, "and then substitute coins."
Five minutes later, however, he exclaimed, "Hang it all! I can't help getting the 2 in a corner. May the florin be moved from its present position?"
"Certainly not."
"Then I give it up."
(The coins in the illustration are a crown in the center (five shillings) and a florin (two shilings) below it. The puzzle predates decimalization by sixty years.)
If you reply, please hide anything that might be a spoiler. I will post the solution later.
https://media.mathstodon.xyz/media_attachments/files/115/747/724/946/377/864/original/cf6d669494e0abe2.png

2025-12-19 15:03:47 UTC

I've just learned that Scott Joplin wrote an opera! (Multiple operas actually, but the others are lost.) It's called “Treemonisha”. https://en.wikipedia.org/wiki/Treemonisha
So far I like the vocal parts. But I don't think I can enjoy the overture: it sounds to me just like Looney Toons music. That's not Joplin's fault, he predates Looney Tones by decades. But I'm not sure I will be able to get past it.
It reminds me a little of the nightmare scenario dreamed up by Douglas Hofstadter, that a previously unknown, but certainly authentic Bach cantata is discovered in a drawer somewhere, the Bach fans all assemble breathlessly to hear its first performance, only to discover that the cantata's main theme is identical to the first seven notes of “Rudolph the Red-Nosed Reindeer”…

2025-12-14 18:16:06 UTC

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@nprofile…stct I was the target audience too—I was ten years old and had been obsessed with Star Trek for years—and I was disappointed. It wasn't the Enterprise I wanted and loved. I wanted the round nacelles with the sparkly things on the front.
I didn't get what I wanted until Strange New Worlds. But it was worth the wait.

2025-12-14 18:04:59 UTC

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@nprofile…stct
There's a Hacker News thread about this in which Typical Hacker News Guy sneers:
> Maybe [Dan] should read about fractals before posting a pedantic message about fermi questions.
and someone has followed up with:
> Google "Dan Piponi", then sit down and think about what you've done.
😆

2025-12-13 21:13:39 UTC

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@nprofile…qn94 Do you know about #lichenSubscribe?

2025-12-09 19:48:34 UTC

What causes this texture?
https://media.mathstodon.xyz/media_attachments/files/115/691/329/286/308/849/original/5019b0b7a99704d7.jpg

2025-12-05 02:33:04 UTC

I'm trying to decide if I have a favorite finite group. Do you?

2025-12-04 15:32:39 UTC

I'm so old…
(“How old are you?”)
I'm so old that Tim O'Reilly once hired me to write a program to download the entire Amazon product catalog.