Christian Lawson-Perfect

Mathematician, koala fan, mathstodon.xyz admin,
⅓ of https://aperiodical.com. He/him

Homepage: http://somethingorotherwhatever.com
Location: Whitley Bay, UK
Pronouns: he/him
Favourite number: 3435

Public Key

npub197gdj7fr20gtagv3w5zvjry79yvaer830d70zxsww8vqskajmhwqq0q2n4

NIP-05 Address

christianp_at_mathstodon.xyz@momostr.pink

Profile Code

nprofile1qqszlyxe0y3485975xgh2pxfpj0zjxwu3nchkl83rg88rkqgtwedmhqprpmhxue69uhhyetvv9ujumt0d4hhxarj9ecxjmnt87gnp9

Publishing to

relay.momostr.pink

Author Public Key

npub197gdj7fr20gtagv3w5zvjry79yvaer830d70zxsww8vqskajmhwqq0q2n4

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Last Notes

2026-05-31 16:21:25 UTC

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is this rational tangles plus FRACTRAN?

2026-05-19 09:39:20 UTC

I know impostor syndrome exists but I am the exception that proves the rule: a genuine impostor

2026-05-15 14:36:06 UTC

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are there Hamiltonian cycles with more interesting symmetry than others? (I haven't thought about this in detail)

2026-05-13 08:02:45 UTC

Hello, I'm from the campaign to launch the word "learnings" directly into the sun. Do you have time for a quick chat about what we're trying to achieve?

2026-05-06 05:02:03 UTC

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Lay down number bars 1, 2, 3, ...
Put the bar as far to the left as you can, as high as you can: if you can stack on top of previous bars, then do so.
The first 25 bars look like the attached image.
The sequence is the lengths of the leftmost bar on each row.
Next two terms are 32, 40.
Now in the #OEIS: https://oeis.org/A395531
https://media.mathstodon.xyz/media_attachments/files/116/476/549/950/434/405/original/c9b796b2eb32275f.png

2026-04-27 11:56:46 UTC

I've come up with another sequence that I can't believe isn't in the #OEIS (#ICBINIOEIS)!
1, 3, 7, 11, 16, 25, ...
Can you guess the next term? Can you guess the general rule?
I haven't done one of these for a while, but the usual rules apply:
* You can ask for hints. Say if you want a big, medium or small hint.
* Put any guesses under a content warning.
* If nobody correctly guesses it, I'll post the answer in a week or so.

2026-04-24 13:52:28 UTC

The accessibility checklist for academic conferences and events that I had a hand in producing now has its own proper address, not under my staff webspace:
https://accessible-events.ncl.ac.uk/
If you work at a university and you're planning any sort of gathering of people, please have a look at it. It contains practical advice about how to make sure people of all sorts are included and able to take part in your event.
#accessibility

2026-04-21 08:11:29 UTC

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yes, etymonline says that "cue" is amongst the spellings used in Old French: https://www.etymonline.com/word/queue

2026-04-21 08:02:23 UTC

Somebody was the first person to write "queue" in a dictionary.
Imagine saying "yes, that is the correct and best spelling for this word: one consonant followed by four vowels, the final three completely redundant."

2026-04-10 04:23:25 UTC

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nice bike, but: you have to keep the printed papers yourself?? Here, the exam service handles everything and lecturers don't see the physical papers until they're ready to be marked.

2026-03-17 15:32:22 UTC

This is wild! Three missing pages of the Archimedes palimpsest have been found in Blois: https://www.cnrs.fr/en/press/lost-page-archimedes-palimpsest-identified-blois-central-france
One of the pages "is covered by an illumination added in the twentieth century, depicting the Prophet Daniel surrounded by two lions, beneath which the ancient text remains to this day inaccessible using conventional methods of examination."
Yes, the *twentieth* century. The footnote says it was added by someone trying to increase its market value.
The palimpsesting never stops!

2026-02-13 11:30:59 UTC

just remembered I was totally going to make a t-shirt saying "ask me about my executive dysfunction"

2026-01-19 08:53:01 UTC

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https://oeis.org/A114260 lists 13 pandigital numbers with this property

2026-01-19 08:15:56 UTC

5702631489 is an interesting number: 5702631489⁴ = 10575 50783 69274 13892 95697 10824 23634 08641.
It's the smallest number 𝑛 such that the decimal digits of 𝑛⁴ make up four copies of the digits of 𝑛.
And did you notice that 5702631489 uses every decimal digit?
Spotted in the new #OEIS sequence https://oeis.org/A391002, which lists numbers like this for each power.

2025-11-26 09:25:03 UTC

I love the big window in my home office - it's got a great view across the park opposite and lets lots of light in.
Except it's the end of November and I live at 55° North, so the sun is shining straight into my eyes.
I have a roller blind, but in order to block the sun I have to roll it so far down that I need to turn the lights on.
It's occurred to me that all I need is a circle just wide enough to block the sun, and to move it throughout the day. The one good thing about the low sun is that it's predictable, so could I rig up something suspended from a belt attached to two servos, like a Makelangelo plotter, to move it throughout the day?
https://media.mathstodon.xyz/media_attachments/files/115/615/231/147/157/445/original/430efa8f0b79338c.jpg

2025-11-23 14:30:16 UTC

It looks like my edit hasn't carried through to bluesky, and I keep getting notifications from the bridge of people pointing out my mistake, so here's a reply saying:
I know it's not credit cards. It's foolscap paper.

2025-10-20 12:53:23 UTC

Is there a public list of certificates granted by Let's Encrypt?
Seconds after using certbot to get a certificate on a new domain, which hasn't been linked to from anywhere, I saw requests to URLs like "/.env" and "/.git/config", and I can't think how else someone would think of trying them.

2025-10-15 06:42:47 UTC

Why is it that I'm happy to spend a couple of days preparing, and a day travelling, to give an academic presentation to half a dozen people, but if I spend an hour making a video and it only gets a couple of hundred views I feel it was a waste of time?
Is it that I don't know *who* the video viewers are?

2025-09-26 14:14:37 UTC

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no, the Romans got that far! See https://www.nms.ac.uk/discover-catalogue/the-romans-in-scotland
Any way, Latin didn't stop when the Romans left. Go for "Edina".
cc @npub19pv…l59y

2025-09-26 05:01:36 UTC

Numerologists take note: tomorrow, 27th September 2025, is a square date in both US and Everywhere Else notation.
5205² = 27092025 and 3045² = 9272025
This is the last time this will happen for a thousand years! (except trivial dates where the US and Everywhere Else forms are the same)
(from @npub1a5g…4kek on math-fun)

2025-09-23 08:56:55 UTC

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wowee, a straight line down a log scale is quite a thing to see!

2025-08-07 18:44:02 UTC

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oops?

2025-08-07 14:40:45 UTC

Is this a synaesthesia thing: does anyone else think that the letters towards the end of the alphabet are less friendly?

2025-07-30 17:40:10 UTC

Does anyone know if there's a way to get Firefox on Ubuntu to offer more than one speech synthesis voice? Is it not finding the others on my system because it's a snap?

2025-07-26 18:03:56 UTC

There must be some entomologists on the fediverse. What's this beastie my daughter found on her windowsill? North East England.
As a guess at a hashtag to get the attention of someone who knows what this is... #fedbugs
https://media.mathstodon.xyz/media_attachments/files/114/920/837/217/847/987/original/eef96dd8fef07154.jpg

2025-07-23 14:27:26 UTC

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do blogs have to have comments? I wouldn't have said so.

2025-06-23 10:27:21 UTC

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(to answer the inevitable question from mathstodon.xyz people: I *could* set up a PeerTube instance linked to mathstodon, but I want to be sure about how much work it is before seriously considering that)

2025-06-23 10:26:21 UTC

A few days ago I spent a little bit of time looking at #PeerTube, to see if it can replace YouTube yet.
I tried and failed to set up an instance on my own server, because it doesn't have enough RAM to keep up with transcoding.
I made an account on cuddly.tube: @npub1tc0…s69n, and had a go at live streaming there but I don't think it kept up. I also uploaded a short video: https://cuddly.tube/w/sMqkvBnzeLk1UtY44nXVeq.
Are there any PeerTube instances that can reliably live stream? I don't mind paying my way in.

2025-06-22 14:11:13 UTC

It's me! On #numberphile! Talking about my favourite polyhedron!
https://youtu.be/3X2aQIMx5bs?feature=shared
After many years never being able to line up doing numberphile video, I was really glad that Brady and I ended up in the same place to do this. I love the animations and especially the sound effects!

2025-06-14 07:51:01 UTC

My kids love their trampoline, but they only spend 50% of the time bouncing up, wasting the other 50% falling down.
That's why I'm not spending another penny on trampoline maintenance until they can improve efficiency and reduce wasted falling time to at most 25%.
This toot is about austerity.

2025-06-11 19:54:58 UTC

EDIT: aperiodic *tilings*, not aperiodic *tiles*. You can arrange these tiles periodically. That'll teach me to take a second to read an abstract!
Whoah! More aperiodic monotiles! https://arxiv.org/abs/2506.07638

2025-06-01 18:47:28 UTC

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what a fun idea!
This was a fun hour: https://integer-credits-sequence.think.somethingorotherwhatever.com/?n=9600

2025-05-24 08:32:35 UTC

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do you have a way of checking your authentication details outside of the router?
Since you've just had fibre put in, I wouldn't be surprised if it was something stupid like they've made a new account instead of moving your old one

2025-05-23 07:53:06 UTC

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the winner of Integer Sequence Review Mêlée Hyper-Battle DX 2000!
https://aperiodical.com/2013/07/integer-sequence-review-melee-hyper-battle-dx-2000-the-grand-finale/
https://media.mathstodon.xyz/media_attachments/files/114/556/058/422/170/833/original/e218d711a426da1e.png

2025-04-29 10:08:43 UTC

The trial of the people accused of cutting down the tree at Sycamore Gap is in progress: https://www.bbc.co.uk/news/live/cvg93k0950pt
They took videos and photos of themselves doing it, which the prosecution have presented. How stupid!
#SycamoreGap #Northumberland

2025-04-12 14:54:29 UTC

I got thoroughly nerdsniped by seeing @npub1ppe…qv2g writing code to render Cuneiform numerals, and I've ended up writing a page that renders numbers in as many different systems as I could think of:
https://numeral-conversion.think.somethingorotherwhatever.com/
I've probably made rookie mistakes in most of them, so if you spot something wrong, please tell me!
https://media.mathstodon.xyz/media_attachments/files/114/325/562/276/926/805/original/999d21203e4e7fc7.mp4

2025-03-20 12:07:05 UTC

Chuffed with this really simple card holder that I designed for my kids' Yoto Player cards.
I've put it on thingiverse in case you want to print your own: https://www.thingiverse.com/thing:6985509
#3DPrinting
https://media.mathstodon.xyz/media_attachments/files/114/194/668/780/397/725/original/04c8a346dd442b1a.jpg
https://media.mathstodon.xyz/media_attachments/files/114/194/668/978/370/373/original/3369f2c87fbc3f37.jpg

2025-03-14 09:43:52 UTC

A whiff of light corruption at the University of Edinburgh: their principal (salary £400k) has taken a second job on the board of a uni spin-off whose sale happened under his tenure, just after a 5% pay rise and while saying that the uni has a huge deficit necessitating job cuts.
He says he'll work for the spin-off in his "personal time". When I do work in my personal time, that time becomes my work time. That's what work is.
https://theferret.scot/edinburgh-uni-staff-rage-principals-second-job-cuts/

2025-02-19 13:55:03 UTC

Does anyone know of any resources about or for mathematicians who are single parents?
I'm in an EDI committee where this came up and they want to spend money on things like posters.

2025-01-28 15:09:57 UTC

A few mathematicians in the UK have set up the Queer, Equality and Diversity Network for Maths. (Name chosen entirely for the acronym: QED)
https://sites.google.com/view/qednetwork/
"The QED network is a community-led effort by UK mathematicians to connect and support LGBTQIA+ members of the UK mathematics community.
The impetus to set up such a network grew out of the 2024 BAMC conference under a drive for increased UK visibility and community for queer people in the mathematics community."
They're on bluesky at https://bsky.app/profile/qedmathsnetwork.bsky.social. I'll see if I can get them over here too 🤞

2025-01-28 09:29:38 UTC

A question about pens.
I'm left-handed and I prefer writing with fountain pens. With ballpoints and the like I produce scratchy nonsense.
For years I've used disposable fountain pens - Pilot V or whatever Bic's pens are called.
I feel a little bit bad about the single-use plastic, but I like having pens in lots of places.
Pilot V-pens are getting more expensive, and I'm not sure if Bic even make theirs any more. I'd like to avoid Amazon if possible.
So, what should I buy? Is there anything non-Amazon for less than £2 per pen, or is there a cheap cartridge pen that I can buy half a dozen of without immediately regretting it?
EDIT: I've used Lamy in the past and I don't enjoy the grip.

2025-01-22 10:53:16 UTC

My employer wants 300 voluntary redundancies across the board, which will become less voluntary if enough people don't volunteer.
The union rep for my school has just sent an email out saying that for us that means 10 academics and 5 support staff will go.
My response:
https://media.mathstodon.xyz/media_attachments/files/113/871/626/324/957/260/original/a75e3bbc5cce512d.png

2025-01-12 09:24:19 UTC

Really chuffed to see an article on the BBC about 2024's #BigMathOff winner and World's Most Interesting Mathematician, Angela Tabiri: https://www.bbc.co.uk/news/articles/c5y80n9jdj5o
It mentions @npub1wg7…hysz by name!

2025-01-09 09:47:53 UTC

My computer has a bug where it keeps showing me science fiction dates like Jan 9, 2025.

2025-01-03 10:51:21 UTC

I've just discovered https://www.map.signalbox.io/ which shows the real-time position of every train on the British mainland.
It will make me a much less anxious traveller next time I'm waiting for a train!

2024-12-22 07:04:51 UTC

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It turned out to be really easy!
In windows, I went to Settings > Recovery options > Advanced startup, and clicked to boot from my Ubuntu partition.
Then I installed and ran boot-disk-repair and it fixed it automatically for me.

2024-12-21 20:03:15 UTC

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it's funny that you're talking about this now - my wife and I have been using "the grain, the fox and the goat" today as codenames while we talk about how to get a big Christmas present into the house without the kids noticing!

2024-12-20 16:32:10 UTC

Windows has overwritten the ruddy bootloader on my laptop! I only keep windows installed to do compatibility testing, and now it's knacked it.
Is it easy to fix? I have an Ubuntu live usb stick

2024-12-18 11:05:53 UTC

Are there any guidelines on designing a *low* contrast mode for web pages?
Searching for "low contrast web design", all I get is pages about how low contrast is bad!
#accessibility

2024-12-17 13:42:54 UTC

This Thursday, Neil Sloane will be giving a talk at the Rutgers Experimental Mathematics Seminar, titled "Eric Angelini's Greatest Sequences".
Abstract:
"Over a period of 20 years, Eric Angelini contributed 1700 brilliant, clever, witty sequences to the OEIS. I will discuss seven of them: "Which terms are primes?", The Jungfrau, Solar Flares, Even Digit Next Bigger, Look Left, Delete Repeated Digits, The Rigidity of the Okapi."
It's on zoom and open to anyone, and will be recoreded: https://sites.math.rutgers.edu/~zeilberg/expmath/

2024-11-25 07:38:09 UTC

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yep, I have all the data and can publish ingoing and outgoing totals. Good idea! Will do it once I've got the kids to school.

2024-11-24 19:03:57 UTC

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At the moment we're covering our costs thanks to generous donations from many mathstodon users.
If you have some money to spare, we'll gratefully receive it at https://ko-fi.com/mathstodon. I promise not to spend it on lobbying to legislate π = 3.

2024-11-24 18:31:12 UTC

mathstodon.xyz: Just a reminder that tomorrow the server will be down for a short while as I move to a new database server.
Everything's set up and ready, so assuming it goes to plan, the downtime shouldn't be more than a few minutes.
If it goes wrong, of course, it's another matter entirely! 🤞

2024-11-16 09:01:01 UTC

My new t-shirt and hoodie have arrived!
The t-shirt uses my own handwriting laid out along the flow lines of a dynamical system.
The hoodie is the spectre aperiodic monotile, fading from green at the top to blue at the bottom. Quoting my wife: "it's just on the right side of too much".
If I put these designs up for sale, would anybody want to buy them?
The code for laying out the handwriting is pretty robust. If I charged a bit more to make a design from your own handwriting, would anyone be interested in that?
#GenArt #MathArt #AperiodicMonotile
https://media.mathstodon.xyz/media_attachments/files/113/491/796/988/432/302/original/66cdb953a166fd70.jpg
https://media.mathstodon.xyz/media_attachments/files/113/491/797/110/901/856/original/d4427f5ed82cc271.jpg
https://media.mathstodon.xyz/media_attachments/files/113/491/797/522/326/452/original/1c46e97020e8768c.jpg
https://media.mathstodon.xyz/media_attachments/files/113/491/797/849/463/063/original/f374d407fcdeb84d.jpg

2024-11-13 10:47:43 UTC

Just had a reminder that in a few weeks I'll be in Bristol, talking to the school of maths about accessible maths material.
https://www.bristolmathsresearch.org/seminar/christian-lawson-perfect/
Are there any Bristolian mathematicians here?

2024-11-05 18:41:33 UTC

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I've decided that running my own email server was more work than it was worth.
Can anyone recommend an email service I can use with my own domain, costing at most £5/month?

2024-11-04 13:22:17 UTC

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had a sudden panic that I'd lost my nice diary app, but I'd checked it in to my git forge and that's backed up on the external HD!

2024-11-04 10:05:42 UTC

Eugh... the SD card in the raspberry pi that powers the cupboard computer didn't survive being powered down for the house move.
Now I need to start from scratch! At least all the real data is on an external HD (and I have backups of that)

2024-10-08 15:31:02 UTC

There's a big wave of spam again. Fortunately, whatever stupid teenager is running it is just using the same script as last time, so my auto-moderator script still works.

2024-10-04 04:37:11 UTC

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hooray, they arrived!

2024-09-24 13:25:49 UTC

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having seen the TeX produced by our senior staff: they could definitely do with a refresher

2024-09-24 13:16:03 UTC

A question for academic matheamaticians: have you ever had any formal training in writing #TeXLaTeX?
Does your department offer anything to colleagues who want to improve their TeX skills?

2024-09-24 10:37:35 UTC

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you could also have a very long post which should get the "show more" button.

2024-09-24 10:33:37 UTC

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that's a really good idea!
I didn't see a post with hashtags at the end, which some clients like to display separately from the main text.

2024-09-14 10:55:13 UTC

Lots of new people on mathstodon.xyz today. Welcome, everyone!
If you'd like people to find you, it's a good idea to write a post with the hashtag #introduction, saying who you are and what you're into.

2024-09-06 08:47:19 UTC

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if you've voted, the majority is currently correct

2024-09-06 08:00:09 UTC

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Now here's a question. If you have a reference knobbly ball or is it morphic equivalent, please don't look at it.
How many times does this pattern repeat around the seam?

2024-09-06 07:57:03 UTC

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But here's an interesting pattern that I don't think I've noticed before.
The ball shows one line of symmetry because it's made from two identical halves, glued together.
There's a repeating pattern along the line: little knobble, two big knobbles, little knobble, gap.
That's interesting!
https://media.mathstodon.xyz/media_attachments/files/113/089/532/399/480/799/original/b94081710d1f438b.jpg

2024-09-06 07:47:47 UTC

The cool thing about this ball (apart from the colour scheme) is that it shows how the icosahedron and dodecahedron are each other's duals - the big knobbles are in the middle of the icosahedron's triangular faces and the little knobbles are in the middle of the dodecahedron's pentagonal faces.
https://media.mathstodon.xyz/media_attachments/files/113/089/496/966/570/640/original/fdc591f75ca220c6.jpg
https://media.mathstodon.xyz/media_attachments/files/113/089/497/613/361/260/original/c2fa123c14cdeddf.jpg
https://media.mathstodon.xyz/media_attachments/files/113/089/497/818/192/375/original/8a22c6dd5a5e1622.jpg

2024-09-03 08:30:29 UTC

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oh hey, it's that meme format I made! This version's by Davide Castelvecchi - https://aperiodical.com/2022/05/didnt-graduate-texts-in-mathematics/

2024-08-19 06:28:33 UTC

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for once, I have one! Still on holiday in the Netherlands.
https://media.mathstodon.xyz/media_attachments/files/112/987/269/573/806/940/original/0f8e0c75c35ed0d5.jpg

2024-08-04 11:55:28 UTC

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don't worry about paying, but yes, give me your address. I'll try to remember to post some next time I'm in the office

2024-08-04 08:54:32 UTC

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I wonder if I could get some mathstodon.xyz stickers to you?

2024-08-02 07:31:31 UTC

For those of you starting to think about preparing your material for the next academic year, here's a reminder of the projects I work on:
Chirun is a tool for producing accessible course material from LaTeX or Markdown source. You can use it through a web interface or as a command-line tool on your own PC.
https://chirun.org.uk/
Numbas (@npub16lz…96kp) is an e-assessment system designed for mathematical subjects. There's a big database of free-to-use existing material and as well as running standalone it integrates with most virtual learning environments.
https://www.numbas.org.uk/

2024-03-26 11:46:38 UTC

Who would know how to make a guess at the answer to this question: is internet traffic pretty much equal numbers of 1s and 0s, or is there noticeably more of one than the other?