Is there a standard term for an infinite set whose complement is also infinite? If not, what would be a good term to make up for it, not too hard to say, and not too easily confused with related words like “finite”, “infinite”, “cofinite”?

Oh, so much to do, and yet getting so little done.

I'm looking in A-Level textbooks for examples of "simplification".

On the first page of content in this EdExcel C1 book, this made me so cross: you're not applying the rule \((a^m)^n = a^{mn}\), you first need \((ab)^n = a^n b^n\), but that rule isn't even listed!

'The difficult thing with quotes on the internet is verifying them' -- Abraham Lincoln

OK, time for bed, early start tomorrow. I can reply to anything I see *very* soon, but otherwise it will have to wait. Night all.

@amiloradovsky Hmm - I see you deleted the toot to which I replied. I'm still interested in your thoughts ...

@amiloradovsky Are you thinking that "around" implies rotation? When looking at a 2D image with a line of mirror symmetry, personal I think of rotating around that line in 3-space to map the image to itself.

A quick questions about nomenclature ... Is there a significant and clear difference between:

"Symmetry about an element"


"Symmetry around an element"


@ColinTheMathmo I've think I'm using \param instead of \epsilon (and set the value of \param in the preamble) because I've already swapped notation: it's typical to use \(\gamma\) for the parameter in question, but I noticed after draft 1 I was already using \(\gamma\) for something else. Let's hope I remembered this and used \param everywhere...

Feedback requested ...

I quickly hacked up a thing recently to "explain" a joke (technically a riddle). Here:

I asked for feedback from a different community and I got a very forthright response:

There's potentially valuable information here, significant amounts of it, and I was wondering was other people's reaction to it might be.

How accurate is it?

We now have a Grace Hopper emojo, :hopper:, for when the bugs are losing

Good judgment comes from experience. Unfortunately, the experience usually comes from bad judgment.

Research shows that 6 out of 7 dwarves are not Happy, and over 14% of them are actually Grumpy.

:chalkdust_scorpion: Do you love maths magazines and Fibonacci numbers? Then you'll love our 8th issue!

There's a fine line between numerator and denominator (and it's called a 'vinculum').

The future is already here - it's just not very evenly distributed. -- William Gibson

@ColinTheMathmo Thank you for this! As a non native speaker I’ve never fully understood this one.

Please consider writing your hashtags in upper camelcase so screen readers have a chance at figuring them out.

#whyistayonmastodon sounds like an giant undecipherable mess of sounds.

#WhyIStayOnMastodon reads out "Why I Stay On Mastodon" 😄

(Reason #44 I stay here: my previous requests like this have been generally well-received, proving that most people are awesome.)

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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.