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Working on answering my own question from a 25-years old paper I wrote while completing my PhD. Getting old? 🙂
doi.org/10.1016/0097-3165(95)9

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Stop using Zip Codes for geospatial analysis: carto.com/blog/zip-codes-spati, via metafilter.com/182600/humans-d

The problem is that they are designed to be convenient for the post office (geographically compact) rather than convenient for demographers (they sometimes combine areas that have quite different groups of people in them). The linked article is by a group selling software for one alternative subdivision that works better, but recommends several others as well.

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Anyone know how to remove followers from a dead and defederated mastodon instance, or from an instance that redirects profile pages off-site?

Although freefedifollowers.ga is now defederated from my instance, my profile still lists many followers from there. The only instructions I can find for removing followers say to go to their profile and block them from there. But their profiles used to redirect to youtube and are now deadlinks. So I can't do it that way.

Are there any other ways?

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@cstrotm

So yeah, it's 2019, someone fixed bugs in the linux kernel's *floppy driver*, and these are 3/5 of the changes:

"floppy: fix out-of-bounds read in copy_buffer
floppy: fix invalid pointer dereference in drive_name
floppy: fix out-of-bounds read in next_valid_format"

#RewriteItInRust #Rust #rustlang

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twitter.com/Foone/status/11516

<< I'd had a tab open with a bunch of text for about 6 hours and I've been meaning to read it and I haven't yet.

the best part? it's about ADHD and how it stops you from doing things. >>

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A formula for designing lenses with no spherical aberration: petapixel.com/2019/07/05/goodb

This seems to have little practical value as there was already a numerical solution, and I don't think it handles chromatic aberration, but it's interesting that there is an analytic formula for these shapes.

Via news.ycombinator.com/item?id=2

@phooky @qrs it is chained to a piece of Amsterdam's street furniture, a pole to block cars. Well, you can't ride away on this bike, so it's OK for a short stop at broad daylight in Amsterdam. Less so for a longer one, but well, the bike is crap...
nl.wikipedia.org/wiki/Vlag_van

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On this day a year ago we started with a small side project to host OpenBSD VMs on OpenBSD.

We couldn't imagine the interest that followed, 283 VMs, 8 hosts dedicated to vmm(4)/vmd(8).

Thank you all! And a huge thanks to @mlarkin, @reyk and Ori Bernstein

#RUNBSD #OpenBSD

@ccppurcell bra-ket is more or less a Hermitean scalar product, IIRC. Nothing needs to be invented there.

@ccppurcell bra-ket was always there in quantum physics, I just wish physicists made an effort to avoid it to be understood by mathematicians

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Turkey has charged over 700 academics with terrorism for signing a peace petition: insidehighered.com/news/2019/0

Among the most severely penalized among them is Tuna Altınel, a mathematician in France who was arrested visiting family in Turkey, and who has now been imprisoned for over 50 days. For more see math.univ-lyon1.fr/SoutienTuna (via cameroncounts.wordpress.com/20)

@ccppurcell well, double vs single pair of brackets is nothing unsual, one e.g. does \(k[[x]]\) for the ring of formal power series in \(x\) over \(k\)

@ccppurcell @jsiehler the usual notation for k-subsets of S is \(\binomial{S}{k}\).
For multisets, add extra pair of (), see tex.stackexchange.com/question

Mathematics, historical nazis 

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NEW: U.S. political operative Paul Manafort received payments for consulting work in Ukraine through over a dozen shell companies thanks to veteran Cypriot lawyer Kypros Chrysostomides, known by some as “Dr. K.”

occrp.org/en/investigations/th

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Today my advisor said:

Reading mathematics is like obesity. If you read too much, then it will only confuse you and will be harmful.

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The slope number of a graph G is the minimum number of distinct gradients of the edges in a straight line drawing of G.

An open problem that is very nice in my opinion: When Δ(G)≤3 the slope number of G is at most 4. For any k there is a graph G with Δ(G)=5 and slope number >k. But what about Δ(G)=4?

Not really my area at all but I like questions like this: where's the boundary?

en.wikipedia.org/wiki/Slope_nu

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