Christian Lawson-Perfect

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

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npub12pjp03a8kt7sdvn4mge9ruf3rcqqdsy9hu7n8zdn3q9dgkhn875s0n9vae

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christianp@mathstodon-xyz.mostr.pub

Profile Code

nprofile1qqs9qeqhc7nm9lgxkf6a5vj37yc3uqqxczzm70fn3xecszk5ttenl2gpz4mhxue69uhhyetvv9ujuerfw36x7tnsw43qz9thwden5te0wfjkccte9ekk7um5wgh8qatzdtv7u3

Publishing to

relay.ditto.pub

relay.mostr.pub

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npub12pjp03a8kt7sdvn4mge9ruf3rcqqdsy9hu7n8zdn3q9dgkhn875s0n9vae

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Last Notes

2026-09-25 13:28:54 UTC

with all these new clever terminal emulators that do things like show images, is there one that could use a different font, depending on which machine I've SSHed into?

2026-08-25 17:31:49 UTC

This is a fun clock: the hours, minutes and seconds marks are on circles of increasing radius in the hyperbolic plane, and there's only one hand. You can find the different markings by moving around the plane.
https://jpivarski.github.io/hyperbolic-map/clock.html

2026-08-12 08:40:01 UTC

First day as a fractionmaxxer. I've already smashed 12432/62160 of the tasks I had to do this morning.
Fractionmaxxing doesn't stop, I'm fractionmaxxing 13619352/3972311.

2026-08-01 20:14:07 UTC

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@nprofile…e2np ooh, what are the train mods? My 5 year old will be very interested

2026-06-17 05:22:36 UTC

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@nprofile…u76z I just tried it on android, and it didn't turn off the new "summarise this page" option. All it turned off was the local translation feature, which I don't mind having.

2026-06-15 19:08:16 UTC

If you're teaching stats and want a perfect example of observation bias, here you go:
https://cyclingindustry.news/cyclists-average-115-mins-a-ride-largely-on-sunday-especially-in-august/

2026-06-03 10:27:40 UTC

Doing a stupid online work training. (important topic, stupid presentation)
I've got all the accessibility options turned on. Which answers are green?
https://media.mathstodon.xyz/media_attachments/files/116/685/692/657/633/499/original/fb028d0050511b4e.png

2026-05-19 09:39:20 UTC

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

2026-05-13 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?

2026-04-27 17:32:30 UTC

Least satisfying sequence in the she #OEIS? https://oeis.org/A395145

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

2026-04-23 13:11:32 UTC

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@nprofile…y789 do you have any thoughts about how borders differ from spaces in the interior of countries? Like, without seeing a literal border post or signs declaring the border, would you usually be able to say you're near a border, based on things like architecture, or the kinds of businesses you see?

2026-04-23 10:10:40 UTC

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@nprofile…2q04 did you see that she's been suspended for calling Keir Starmer a liar? https://www.bbc.co.uk/news/articles/cdrm752l03xo
cc @nprofile…y0gw

2026-04-17 08:25:16 UTC

I had an intrusive thought about making a text adventure using a dataset of UK towns:
https://uk-the-text-adventure.think.somethingorotherwhatever.com/
https://media.mathstodon.xyz/media_attachments/files/116/419/085/894/512/334/original/136a9c61e03a41c4.png

2026-04-14 07:40:14 UTC

Professionals call this a wibbly-wobbly mathsy-wathsy diagram.
(from https://orca.cardiff.ac.uk/id/eprint/182750/)
https://media.mathstodon.xyz/media_attachments/files/116/401/921/672/617/559/original/664f2dacfef7dd5a.png

2026-03-27 10:12:48 UTC

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@nprofile…2q04 ahh, I was looking at a different thing: the JSON dump file from https://www.givefood.org.uk/api/, which seems to have both locations and organisations.
I suppose it doesn't really matter, because both kinds of thing to count can be misleading: a few big organisations with lots of small locations could look like very few "food banks" or lots of "food banks", depending on which you count.

2026-03-27 09:51:18 UTC

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@nprofile…2q04 first of all, thanks for continuing to do this.
Something's up with the food banks data: a couple of constituencies I tried go to a missing page on givefood, for example Argyll, Bute and South Lochaber. And the count of food banks doesn't seem to match the number shown on givefood for several constituencies, for example Newcastle upon Tyne East and Wallsend which has 2 on your map but 4 are listed on givefood.

2026-03-05 14:42:40 UTC

I'm preparing a talk on accessibility of e-assessment, so I'm dredging my brain for memories of inaccessible questions I've seen.
If you have any suggestions, please tell me about them!

2026-02-17 11:57:00 UTC

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Nope, it's gone. I have a version from last May, but everything since is lost.

2026-02-17 11:06:22 UTC

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Why didn't I back it up? It takes a moment to set up. 😭

2026-02-17 11:04:28 UTC

Ahhhhhhhhh
I've accidentally deleted the kids' Minecraft world. I have no backups. I feel sick.
I deleted the directory containing it last Friday. I'm going to try a recovery usb and extundelete, but that's the only hope I'm clinging on to.

2026-02-17 07:26:43 UTC

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@nprofile…e5jr I love it so much I've got the t-shirt: https://aperiodical.teemill.com/product/im-greater-than-equal-to-or-less-than-you/Light%20Purple/

2026-02-15 08:14:41 UTC

It's a one-line #OEIS comment, Michael, how many edits could it take? 10?
https://media.mathstodon.xyz/media_attachments/files/116/073/637/907/489/864/original/cb9d032017e82c6e.png

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"

2026-02-12 11:04:37 UTC

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@nprofile…8tlc I hope never to find out

2026-02-12 10:30:56 UTC

Why is Rington's hot chocolate so yucky?

2026-02-11 17:26:47 UTC

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@nprofile…74xv I think that's exactly what's happening, but our SSO is handled by Microsoft so you'd hope they could join things up

2026-02-10 16:45:55 UTC

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@nprofile…r0xq I bet there's a line "update MathJax" on their issue tracker, under a tonne of more urgent "deal with the nonsense the CS people are doing" issues

2026-02-09 14:09:10 UTC

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I also did a video about it: https://media.aperiodical.com/number-builder

2026-02-09 14:00:24 UTC

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I also did a video about it: https://media.aperiodical.com/number-builder

2026-02-09 14:00:07 UTC

I've blogged! I've actually sat down and written a post on a blog!
It's about the game I wrote over the weekend, Number Builder.
https://aperiodical.com/2026/02/number-builder-can-you-build-up-from-1-to-the-target/

2026-02-09 10:06:22 UTC

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I know we're rapidly leaving the time of year when this matters, but I'm really starting to think this is worth doing

2026-02-09 09:52:12 UTC

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@nprofile…y789 even ignoring the technical reasons not to cross the Irish sea twice, there are topological reasons not to make a loop line, aren't there? Like, we could currently have a loop Glasgow → Edinburgh → London → Liverpool → Manchester → Glasgow, but we don't, we have two separate lines.

2026-02-07 09:57:06 UTC

What a day to find out that #elmlang Ints are 32-bit!

2026-02-06 15:16:42 UTC

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@nprofile…yree Uploading to the arXiv as an independent researcher is very hard: they've had so many crank submissions that you have to jump through a lot of hoops to be allowed to submit.
You'll find plenty of independent researchers at https://vixra.org/. Most of it's nonsense, but there's the occasional cogent thing in there.

2026-02-06 14:18:16 UTC

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@nprofile…yree I don't think this is true. There are plenty of people who do mathematical research as a hobby. You might not be looking in the right places.

2026-02-06 14:03:24 UTC

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Speedrunners might like to look at https://oeis.org/A173419

2026-02-06 10:34:28 UTC

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I think animating this as a big tower would be fun

2026-02-06 10:26:57 UTC

I have spent too much time this morning making a game about building numbers: https://number-builder.think.somethingorotherwhatever.com/

2026-02-05 18:38:37 UTC

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@nprofile…wwtv I'm not happy about it

2026-02-05 16:16:34 UTC

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@nprofile…llgf hah, nothing so complicated!

2026-02-05 14:56:36 UTC

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@nprofile…nmnk @nprofile…7yy4 @nprofile…feml thanks.
I did have the thought that I should just physically make these parts inefficiently, and then pack them by squishing with my hands and taking a top-down photo when they stop moving!

2026-02-05 14:26:26 UTC

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@nprofile…4cw8 I did this by eye in inkscape

2026-02-05 14:07:27 UTC

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@nprofile…7yy4 @nprofile…feml I've just given it a go, and it doesn't seem to be getting anywhere near a good packing. Oh well!

2026-02-04 18:21:58 UTC

Another #BeachSpectres update: I've had another go at using the laser cutter to make a layered Spectre. I've also realised something interesting about the construction of the shape.
https://beachspectres.com/news/2026-02-04-update-4/

2026-02-04 15:17:16 UTC

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@nprofile…8npm eeeeeeeppp

2026-02-04 12:46:39 UTC

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@nprofile…feml super, thanks!

2026-02-04 12:30:33 UTC

I have a few complicated shapes that I want to #LaserCut. Is there an open source tool that will pack them in as small an area as possible?

2026-02-04 11:11:45 UTC

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@nprofile…kwrt me or one of my descendants

2026-02-04 10:01:22 UTC

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guess who just asked me to sign in again

2026-02-04 08:03:56 UTC

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The start of this thought was: can I count the number of Es on mastodon (its oulipo sad count)

2026-02-04 07:54:56 UTC

You have 406 unresolved childhood traumas.
⌷ Start crying now
⌷ Remind me at bedtime

2026-02-04 07:52:33 UTC

I had a useless thought in the shower:
I wonder what the entire corpus of toots looks like, in alphabetical order?
Wary of accidental PII disclosure, I've begun by writing all of my own statuses in alphabetical order: https://checkmyworking.com/posts/2026/02/every-toot-ive-ever-written-in-alphabetical-order/

2026-02-03 13:17:02 UTC

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@nprofile…lsk9 mojibake?!

2026-02-03 09:39:59 UTC

Microsoft Teams go 24 hours without asking me to sign in again challenge (impossible)

2026-01-31 18:03:10 UTC

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@nprofile…udvu too low in the sky for us 😔

2026-01-30 10:54:11 UTC

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@nprofile…w4kc only myself 😔

2026-01-29 20:19:42 UTC

103638 is an interesting number: when written in decimal, 103638! contains the substring 0123456789. No smaller factorial does.
From new #OEIS sequence https://oeis.org/A385673

2026-01-29 15:45:32 UTC

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@nprofile…ydhp well, the realisation is that it is optimisation: I'd assumed I *had* to put those constraints in or the thing wouldn't work, but it turns out I don't!

2026-01-29 15:40:21 UTC

I've had a #FreeCAD insight: be clever *after* you've got the structure sorted.
Every time I've tried to make something in the past, I've set up all the constraints and parameters as I go.
I've just had a go at making something "by eye", getting the rough shapes I need, and now going back and setting the constraints is easy peasy!

2026-01-29 13:51:46 UTC

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@nprofile…8262 where did you get that there's a setting?
Looking at the source code (https://github.com/WordPress/gutenberg/blob/a2338dffffbcfcdf7b05d087e2178d82847ca0ba/packages/block-library/src/math/edit.js), I can't see how it would take MathML input: it looks like it always tries to run it through the LaTeX to MathML routine.
You can put MathML in the custom HTML block, though.
https://media.mathstodon.xyz/media_attachments/files/115/978/709/133/928/711/original/3cf26930598b7d0c.png
https://media.mathstodon.xyz/media_attachments/files/115/978/709/474/088/392/original/14ac310b3bfa539c.png

2026-01-29 13:42:44 UTC

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@nprofile…yhyk is this the mathstodon.xyz web interface? Which browser and OS are you using?

2026-01-29 10:24:14 UTC

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the fun thing I was working on last week was, of course, an urgent new thing that distracted me from the really fun thing I was working on two weeks ago. The really fun thing has no deadline, but I hope I'll get back to it sooner rather than later.

2026-01-29 10:23:12 UTC

#elmlang is lovely but I'd really like convenient lenses for updating records. All it's missing is a generic setter function, like the generic getter function `.key : { key: a } -> a`.

2026-01-29 10:07:24 UTC

Gang, it's only Thursday morning and I've already worked through the week's Emails That Require Attention, so I can get back to the fun thing I was working on last week! Hooray!

2026-01-29 08:38:18 UTC

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Maybe nobody!
If there's a smaller variance in the women's finishing times, then it's possible that even though their mean is less than the men's, they're bunched on the right side of the cutoff so that the same proportion of women as men are on the wrong side. It's even possible that the change could affect men more than women.
This kind of situation comes up a lot when talking about things like test scores and hiring discrimination. Someone might say "men have a higher average score than women, so I'll only recruit men". But if there's a higher variance in men's scores than women's, that could actually result in more people with low scores being interviewed.
(2/2)
https://media.mathstodon.xyz/media_attachments/files/115/977/465/139/021/340/original/8c08e96b5a7102c0.png

2026-01-29 08:22:14 UTC

This article about a change to the Montane spine race - https://www.bbc.co.uk/news/articles/cew8z1k1p2no - brings up an interesting stats question.
They're shortening the cut-off time, so participants have less time to complete the race. Several people in the article say they're concerned that it'll affect more women than men, because women are slower on average.
But the organisers say they modelled it using the real times from this year, and the number of women affected by the new cutoff is proportional to the number of women who started.
So who's wrong?
(1/2)

2026-01-28 15:05:32 UTC

How many white men can we fit in this diversity committee?

2026-01-28 14:20:03 UTC

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@nprofile…g03k by @nprofile…djxg!

2026-01-28 13:37:08 UTC

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@nprofile…llgf hah, yes, exactly!

2026-01-28 12:44:59 UTC

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OK, fair enough, there's 199GB of stuff in this game.

2026-01-28 11:28:05 UTC

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@nprofile…m8gf yeah, it feels like if anything is going to replace TeX, it'll be Typst.
There are some baffling language design choices that have put me off, but I haven't looked deeply because I'm waiting for decent HTML output.

2026-01-27 14:38:44 UTC

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@nprofile…3n8d the web management interface is woeful, but technically I'm happy with them. Compared to GoDaddy, I 100% recommend them.

2026-01-27 14:32:42 UTC

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I was passed on to "the second level of support" and they've just changed the address, no ID necessary.
If I was a particularly awkward individual, I would take this as motivation to ask the information commissioner to look at their GDPR compliance. Where would my passport photo have gone, if I'd sent it?

2026-01-27 10:12:35 UTC

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@nprofile…xyvp I always hate days like that. It's supposed to chuck it down all say here and I've got two ill kids at home.
Somehow the days when there's a break in the rain just for drop off don't feel as notable.

2026-01-26 07:47:03 UTC

#OEIS sequence that sounds like a Star Trek plot point: "Nullspace dimension of the periodic XX Heisenberg chain with n > 1 sites."
https://oeis.org/A392387

2026-01-24 20:45:28 UTC

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@nprofile…r9em me too!

2026-01-24 19:52:04 UTC

9814072356 is an interesting number: it's the largest square number (99066²) with no repeated digits.
From https://oeis.org/A392242, just added to the #OEIS.

2026-01-24 11:04:40 UTC

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@nprofile…my3l what's DCS?

2026-01-24 10:53:31 UTC

umm, red dead redemption 2 is 119GB?!?!

2026-01-23 12:58:24 UTC

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@nprofile…chm0 if only they had access to some good literature on effective search algorithms and metadata handling...

2026-01-23 10:23:12 UTC

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@nprofile…ymk3 I'm not in the know, so my first question is: do you have to assume 𝑥≥1 ?

2026-01-21 16:13:20 UTC

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@nprofile…v0c7 start with 1, multiply by 7, keep only the last digit.
Can you pick a starting number where this process doesn't eventually end?

2026-01-21 16:03:29 UTC

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@nprofile…ggfl Catterick and Northallerton look like the obvious places

2026-01-21 16:02:31 UTC

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@nprofile…yctt they're mostly to the north of me. I'd go north-west at best.

2026-01-21 14:27:02 UTC

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@nprofile…nuf5 @nprofile…fx72 yes, but they're more capable than anyone else of making a system with lower per-transaction costs.
Other microtransaction systems tend to work on the model of loading up a "wallet" with money, then they work out how to distribute it periodically. But that's not categorically different than what credit cards do.

2026-01-21 13:53:08 UTC

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@nprofile…74xv yes, I want directions that subdivide a region, instead of words that make a single direction more precise.

2026-01-21 13:52:20 UTC

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@nprofile…74xv no, if they're all part of the name, I'll take them

2026-01-21 13:49:11 UTC

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@nprofile…4257 that has to be the winner!

2026-01-21 13:44:54 UTC

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if anyone can beat the three compass directions in the South East Northumberland Rail User Group, I'd be very happy to see it: https://www.senrug.co.uk/

2026-01-21 13:35:19 UTC

One thing we love to do in England is to compose compass directions to get really specific about the region we're interested in.
Durham Mathematics School says that it will take students from North North Yorkshire: https://durham-mathematics-school.org.uk/about-us/.
They don't narrow down Northumberland, but I can't see many students travelling down from Berwick: at 116km from Durham, it's further away than Selby in South North Yorkshire.

2026-01-21 11:33:30 UTC

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@nprofile…v0c7 if he's met powers before, then the base-10 münchausen numbers are fairly easy to explain, and not much harder to show they're finite: https://oeis.org/A046253

2026-01-21 09:45:06 UTC

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@nprofile…fx72 yeah, I think it definitely needs the network effect.
I find it interesting that mastercard or visa haven't tried to introduce a micropayments system, which would get them more of the money that currently only comes via ad networks with a significant cut taken out

2026-01-21 09:20:42 UTC

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@nprofile…4a4h somebody's got some money, and I want a millionth of it

2026-01-21 09:16:09 UTC

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@nprofile…09hu 😡

2026-01-21 08:54:57 UTC

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anybody who mentions cryptocurrency gets an immediate block, btw

2026-01-21 08:53:01 UTC

What happened to micropayments? Did everyone just decide it was too much friction, so went with ads instead?

2026-01-20 14:49:27 UTC

The EDI team here publish a newsletter using Microsoft Sway.
It's horrendously inaccessible. Fortunately, they have an "accessibility view"!
Unfortunately, the accessibility view keeps popping up this dialog telling me to refresh the page because I took too long to read it.
That fails several #WCAG criteria: https://www.w3.org/TR/WCAG22/#enough-time

2026-01-20 05:23:14 UTC

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@nprofile…9sln I'm not aware of any other issues, sorry.

2026-01-19 19:07:44 UTC

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@nprofile…vcny how much time are you spending on these? I decided to give it a go today before picking the kids up and in ten minutes got as far as "I can divide a square into 16×16 and use two hex digits as coordinates"