Solution

Just two days after her first video,
@jensimmons is back with another video about the #accessibility #inspector in the
#Firefox #Developer #Tools. This time, she looks at color contrast, color vision deficiency simulator, underlined links because they're beautiful. #a11y #webdev

Today at lunch, I've learned about the Trash Compaction problem: Can you push objects on a grid into the compact shape of a rectangle if you're only allowed to push all objects from one side simultaneously. Akitaya, Aloupis, Löffler, and Rounds showed that the problem is NP-complete.

The fun variant of this problem talks about pushing around coconuts with a giant coconut pusher... Here are some neat slides: staff.science.uu.nl/~loffl001/

@11011110 this reminds me of a nice puzzle:
I have a jar containing tea bags, which come in pairs. When I want to make a cup of tea, I reach into the jar and pull a random bag out. If it's part of a pair, I rip it and put the other bag back.
I can't remember how many times I've made tea since filling the jar. What's the probability that I pull out a single tea bag next time?

You really get an appreciation for the noncommutativity of 3d rotations when you've pulled a muscle in your lower back.

I made a regex to match all multiples of 7, but it was >10,000 characters so grep couldn't handle it.

UK residents: register to vote now, like right now

gov.uk/register-to-vote

I've made a new puzzle: the Hexiamond lantern

thingiverse.com/thing:3944186

@ctdunc it's a classic!

ukpol but not recent

ukpol but not recent

@quarky I have protanopia, which means my eyes don't pick up red light very well. That means I find it hard to distinguish colour combinations like blue/purple or green/yellow.
This app can give me a name for a colour, so I could use it to for example pick a green t-shirt instead of a yellow one.
It doesn't give me a sense of which colours go well together, or which colours look 'nice'.
I used to have an app which simulated what I see in realtime, but it was for an old version of android

@xaphania Color Blind Pal - play.google.com/store/apps/det
It can identify colours (but it's got so many names that it's quite jittery) and filter so you can see differences, if not real colours. It doesn't have a simulate mode, which means I can't show others what I see.

Just using my colourblind app to help me appreciate the beauty of autumn leaves 👍 😎 👍

I've just discovered that the character " (a set of double quotes) is a valid HTML attribute name in Firefox.
e.g. <span "="amazing"></span>

@cpsdqs because it's easy to implement in an interpreter?
I can see the train of thought for someone new to programming: I have a variable called $x, and a variable called$y, and I want to use one or the other based on some changing condition. So, I should be able to ask for a variable with a name which is itself a variable

@cpsdqs oh wow! That feels very unsafe

Thinking Outside the Plane: metafilter.com/183649/Thinking

Interesting roundup of 3d solutions to 2d problems, starting with Tarski's plank problem: Can you cover a diameter-$$n$$ disk with fewer than $$n$$ unit-width strips?

Sadly, they missed the 3d proof of Desargues' theorem: en.wikipedia.org/wiki/Desargue

There's also a 2d-3d connection with Miquel's six-circle theorem but I think it goes the other way: 11011110.github.io/blog/2006/0

A Mastodon instance for maths people. The kind of people who make $$\pi z^2 \times a$$ jokes. Use $$ and $$ for inline LaTeX, and $ and $ for display mode.