@ColinTheMathmo@mathstodon.xyz avatar

ColinTheMathmo

@ColinTheMathmo@mathstodon.xyz

Fulltime freelance provider of outreach and enhancement in maths ... I talk a lot. About maths.

I talk about other stuff too, like ballroom dancing, juggling, unicycling, education, engineering, software, and "other things".

But mostly about maths.

I tend to follow back, but only if you have something in your profile.

This profile is from a federated server and may be incomplete. Browse more on the original instance.

ColinTheMathmo, to random
@ColinTheMathmo@mathstodon.xyz avatar

Don't use WhatsApp:

"WhatsApp messages are end-to-end encrypted, but user data is not only about messages. That also includes the metadata such as user location, which contacts the user is communicating with, the patterns of when the user is online, etc. This metadata according to your privacy policy is indeed used for targeted ads across Meta services."

-- https://x.com/mysk_co/status/1795210609153163374

ColinTheMathmo,
@ColinTheMathmo@mathstodon.xyz avatar

What's the alternative? I use Signal, and it's nice to see it recommended in the Forbes article.

"But for those worried by user tracking—even from metadata, or those who simply want to use the most private, secure and cleanest platforms, then there’s always a case to switch WhatsApp for Signal."

-- https://www.forbes.com/sites/zakdoffman/2024/05/28/elon-musk-fights-back-as-whatsapp-denies-harvesting-his-data-every-night/

ColinTheMathmo,
@ColinTheMathmo@mathstodon.xyz avatar

@laslab It's a source of constant and consistent annoyance to me that circumstances require that I keep a presence in both the FBBBS and FFB.

It's minimal, but for me it is regrettably unavoidable.

ColinTheMathmo, to random
@ColinTheMathmo@mathstodon.xyz avatar

Gosh ... I liked this one ...

754

➡️➡️➡️➡️➡️➡️➡️➡️➡️➡️➡️➡️➡️➡️➡️➡️

https://www.andrewt.net/puzzles/cell-tower/?p=754

Current streak: 100 (Fermium)

Best streak: 100

ColinTheMathmo, to random
@ColinTheMathmo@mathstodon.xyz avatar

I've seen mathematicians take a piece of paper, draw an arrow, not even a domain or image, stare at it, then say 'No that's not it', scrap the paper and start all over again... -- https://x.com/Friteszilla/status/1794489258436092280

amcsquared, to random
@amcsquared@mathstodon.xyz avatar

Ahhhhhhhhh 754

➡️➡️➡️➡️➡️➡️➡️➡️➡️➡️➡️➡️➡️➡️➡️➡️

https://www.andrewt.net/puzzles/cell-tower/?p=754

ColinTheMathmo,
@ColinTheMathmo@mathstodon.xyz avatar

@boxofrain Somehow it was a nice one.

It's a bizarre thing, how some are "nicer" than others. I don't really know what that means ...

CC: @KarenCampe @amcsquared

ColinTheMathmo, to random
@ColinTheMathmo@mathstodon.xyz avatar

Add a quantity to itself, then divide by two, and not get back the original!

Tony explains more ...

https://tonysmaths.blogspot.com/2024/05/a-puzzle-from-my-childhood.html

vesatimonen, to random
@vesatimonen@mathstodon.xyz avatar

Dissecting a mitre.

ColinTheMathmo,
@ColinTheMathmo@mathstodon.xyz avatar

@pbsds Classical dissection problems permit reflections of pieces ... this is a completely valid solution

So the next problem/question is whether there is a solution that does not have any reflections.

CC: @vesatimonen

ColinTheMathmo, (edited ) to random
@ColinTheMathmo@mathstodon.xyz avatar

An answer to a 100-year-old puzzle. I say an answer, because there is still part of the question that's open.

EDIT: The author/discoverer is here on Mathstodon!

https://mathstodon.xyz/@vesatimonen

And his post of this:

https://mathstodon.xyz/@vesatimonen/112513347111148808

ColinTheMathmo,
@ColinTheMathmo@mathstodon.xyz avatar

@morganist This is a question in the field. Under the usual conventions it is acceptable for a dissection to reflect a piece, and then you have the second challenge of trying to find a dissection that does not require a reflection.

The of the original question as coming in two parts: Find any dissection, then find a dissection that doesn't use reflection.

"There is some debate as to the permissibility of flipping pieces. While it is reasonable to prefer an unflipped dissection over a flipped one if both use the same number of pieces, it is also reasonable to separately list the best known dissections flipped and unflipped when the number of pieces differ"

-- https://mathworld.wolfram.com/Dissection.html

ColinTheMathmo,
@ColinTheMathmo@mathstodon.xyz avatar

@tretron I don't see how someone with a welder could create a one piece solution.

Can you explain?

ColinTheMathmo,
@ColinTheMathmo@mathstodon.xyz avatar

@tretron Well yes, I get that with a welder you can make one piece out of many, but I still don't see how this is a solution. You still need to cut up the original, so the problem remains.

ColinTheMathmo,
@ColinTheMathmo@mathstodon.xyz avatar

@theohonohan We still have the questions of:

(a) can it be done with only 3 pieces (though that feels like an obvious "no");

(b) can be be done in 4 pieces without reflections (still open).

I'm not sure what part of my phrasing you might feel to be "torturous".

ColinTheMathmo,
@ColinTheMathmo@mathstodon.xyz avatar

@theohonohan Ah! Sorry, I mis-interpreted.

And, well, the wording was, in part, intended to prevent people from thinking the matter was fully settled without giving away too much about what is settled, and what exactly might still be unresolved.

ColinTheMathmo, to random
@ColinTheMathmo@mathstodon.xyz avatar

Despite our artistic pretensions, sophistication, and many accomplishments, we owe our existence to a six inch layer of topsoil and the fact that it rains -- Paul Harvey (lightly edited)

ColinTheMathmo, to random
@ColinTheMathmo@mathstodon.xyz avatar

ARGH !!!

You'd think I'd learn ...

753

⬜⬜⬜⬜⬜⬇️⬜⬜⬜⬜⬜⬜⬜⬜⬜
➡️➡️➡️➡️➡️⏹️➡️➡️➡️➡️➡️➡️➡️➡️➡️

https://www.andrewt.net/puzzles/cell-tower/?p=753

Current streak: 99 (Einsteinium)

Best streak: 99

ColinTheMathmo,
@ColinTheMathmo@mathstodon.xyz avatar

@lgarron It was a good one ...

ColinTheMathmo, to random
@ColinTheMathmo@mathstodon.xyz avatar

In about half an hour, #UK_ISS #ISS pass, starting at 22:12:13, duration 180 secs, visible, Magnitude -1.3

ColinTheMathmo, to random
@ColinTheMathmo@mathstodon.xyz avatar

Some passes of the #ISS visible from the UK overnight - I'll post alerts closer to the time - #UK_ISS

ColinTheMathmo, to random
@ColinTheMathmo@mathstodon.xyz avatar

Having seen this mentioned, I had to try it for myself. Asking Google for "Fruits that end in -um".

« Applum.
« Bananum.
« Strawberrum (really any of the fruits ending in *-berrum’)
« Tomatum.
« and Coconut.

I particularly like "Coconut".

ColinTheMathmo, to random
@ColinTheMathmo@mathstodon.xyz avatar

Satisfying ...

752

➡️➡️➡️➡️➡️➡️➡️➡️➡️➡️➡️➡️➡️➡️

https://www.andrewt.net/puzzles/cell-tower/?p=752

Current streak: 98 (Californium)

Best streak: 98

ColinTheMathmo, to random
@ColinTheMathmo@mathstodon.xyz avatar

We don't make mistakes, we just have happy accidents. -- Bob Ross

johncarlosbaez, (edited ) to random
@johncarlosbaez@mathstodon.xyz avatar

In the real world, the rope in a knot has some nonzero thickness. In math, knots are made of infinitely thin stuff. This lets mathematical knots be tied in infinitely complicated ways - ways that are impossible for knots with nonzero thickness! These are called 'wild' knots.

See the wild knot here? There's just one point where the stuff it's made of needs to have zero thickness. So we say it's wild at just one point. But some knots are wild at many points.

There are even knots that are wild at every point! To build these you need to recursively put in wildness at more and more places, forever. This is hard to draw. I'd really like to see a good try.

Wild knots are extremely hard to classify. This is not just a feeling - it's a theorem. Vadim Kulikov showed that wild knots are harder to classify than any sort of countable structure that you can describe using first-order classical logic with just countably many symbols!

Very roughly speaking, this means wild knots are so complicated that we can't classify them using anything we can write down. This makes them very different from 'tame' knots - knots that aren't wild. Yeah, tame knots are hard to classify, but nowhere near that hard.

(1/3)

https://www.youtube.com/watch?v=o7U3yvMF8Sw

ColinTheMathmo,
@ColinTheMathmo@mathstodon.xyz avatar

@johncarlosbaez Certainly inside "Topological"

ChuckMcManis, to random
@ChuckMcManis@chaos.social avatar

Hey is there a web client that will do language translation of toots?

ColinTheMathmo,
@ColinTheMathmo@mathstodon.xyz avatar

@ChuckMcManis I've not checked, but I think on our instance (Mathstodon.xyz) we have translation enabled. If someone has one language set in their profile, and someone with a different language views that post, then a "translate" link appears.

But this is, I think, on an instance by instance basis, and it relies on people setting their "home" language in their profile.

(This may be wrong, but I think it's correct-adjacent)

ColinTheMathmo,
@ColinTheMathmo@mathstodon.xyz avatar

@dougmerritt I've followed @ChuckMcManis for a long time. Likely at some point something he said popped into my timeline, and the way the FediVerse works it's a Good Thing(tm) to follow people and grow one's network. So I did.

He doesn't follow me, though, so we can't be said to know each other.

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