Did you know it's possible to cut a hole in a cube such that an identical cube can fit inside it? Really! It's called "Rupert's Property." *All Platonic solids are Rupert!* Except one new shape, which *cannot* fit inside itself. This eldritch polygon is called a Noperthedron!
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If you'd like an essay-formatted version of this thread to read or share, here's a link to it on pluralistic.net, my surveillance-free, ad-free, tracker-free blog:
pluralistic.net/2025/08/30/mer…
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This entry was edited (4 days ago)
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Cory Doctorow
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"Noperthedron" is the best coinage I've heard in months, which makes it a natural to open this week's linkdump, a collection of the links that piled up this week without making it into my newsletter. This is my 33d Saturday linkdump - here's the previous 32 editions:
pluralistic.net/tag/linkdump/
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linkdump – Pluralistic: Daily links from Cory Doctorow
pluralistic.netCory Doctorow
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Speaking of eldritch geometry? Perhaps you've heard that Donald Trump plans to add a 90,000 sqft ballroom to the (55,000 sqft) White House. As Kate "McMansion Hell" Wagner writes for *The Nation*, this is a totally bullshit story floated by Trump and a notorious reactionary starchitect, and to call it a "plan" is to do unforgiveable violence to the noble art of planning:
thenation.com/article/culture/…
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No, the White House Is Not Getting a 90,000-Foot Extension | The Nation
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Cory Doctorow
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Wagner is both my favorite architecture critic and the only architecture critic I read. That's because she's every bit as talented a writer as she is a perspicacious architecture critic. What's more, she's a *versatile* writer. She doesn't just write these sober-but-scathing, erudite pieces for *The Nation*; she has, for many years, *invented* the genre of snarky Zillow annotations, which are *convulsively* funny and trenchant:
mcmansionhell.com/
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McMansion Hell
TumblrCory Doctorow
in reply to Cory Doctorow • • •Sensitive content
At the EFF, we often find ourselves at the center of in big political legal fights; for example, we were the first group to sue Musk and DOGE:
eff.org/press/releases/eff-sue…
Knowing that I'm part of this stuff helps me get through tough times - but I'm also so glad that we get to step in and defend brilliant writers like Wagner, as we did a few years ago, when Zillow tried to use legal bullying tactics to make her stop being mean to their shitty houses:
eff.org/deeplinks/2017/06/mcma…
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EFF Sues OPM, DOGE and Musk for Endangering the Privacy of Millions
Electronic Frontier FoundationCory Doctorow
in reply to Cory Doctorow • • •Sensitive content
If this kind of stuff excites you as much as it excites me and you're in the Bay Area, get thee to the EFF Awards (or tune into the livestream) and watch us honor this year's winners: Just Futures Law, Erie Meyer, and the Software Freedom Law Center, India:
eff.org/deeplinks/2025/08/join…
So much of the activity that EFF defends involves *writing*. The web was written into existence, after all, both by the coders who hacked it together and the writers who filled it up.
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Join Your Fellow Digital Rights Supporters for the EFF Awards on September 10!
Electronic Frontier FoundationCory Doctorow
in reply to Cory Doctorow • • •Sensitive content
I've always wanted to be a writer, since I was six years old, and I'm so lucky to have grown up through an era is which the significance of the written word has continuously expanded.
I was equally lucky to have writing teachers who permanently, profoundly shaped my relationship with the written word.
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Cory Doctorow
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I've had many of those, but none were so foundational as Harriet Wolff, the longest-serving English teacher at Toronto's first alternative school, SEED School, whence I graduated after a mere seven years of instruction.
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Cory Doctorow
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Harriet was a big part of why I spent seven years getting a four year diploma. She was such a brilliant English teacher, and presided over such an excellent writing workshop, that I felt like I still had so much to learn from high school, even after I'd amassed enough credits to graduate, so I just *stuck around*.
Harriet died this summer:
obituaries.thestar.com/obituar…
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HARRIET MARY WOLFF Obituary | Toronto Star
obituaries.thestar.comCory Doctorow
in reply to Cory Doctorow • • •Sensitive content
We hadn't spoken much over the past decade, though she did come to my wedding and was every bit as charming and wonderful as I'd remembered her. Despite not having spoken to her in many years, hardly a day went by without my thinking of her and the many lessons she imparted to me.
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Cory Doctorow
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Harriet took a very broad view of what could be good writing. Though she wasn't much of a sf fan, she always took my sf stories seriously - as seriously as she took the more "literary" fiction and poetry submitted by my peers. She kept a filing cabinet full of mimoeos and photocopies, each excellent examples of various forms of writing. Over the years, she handed me everything from Joan Didion essays to especially sharp op-eds from Time Magazine, along with *tons* of fiction.
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Cory Doctorow
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Harriet taught me how to criticize fiction, as a means of improving my understand of what *I* was doing with my writing, and as a way of exposing other writers to new ways of squeezing their big, numinous, irreducible feelings out of their fingertips and onto the page. She was the first person I called when I sold my first story, at 17, and I still remember standing on my parents' lawn, cordless phone in one hand and acceptance letter in the other, and basking in her approval.
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Cory Doctorow
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Harriet was a tough critiquer. Like many of the writers in her workshop, I had what you might call "glibness privilege" - a facility with words that I could use to paper over poor characterization or plotting. Whenever I'd do this, she'd fix me with her stare and say, "Cory, this is *merely clever.*" I have used that phrase countless times - both in relation to my own work and into the work of my students.
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Cory Doctorow
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Though Harriet was unsparing in her critiques, they never stung, because she always treated the writers in her workshop as her peers in a lifelong journey to improve our craft. She'd come out for cigarettes with us, and she came to every house party I invited her to, bringing a good, inexpensive bottle of wine and finding a sofa to sit on and discuss writing an literature.
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Cory Doctorow
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She invited me to Christmas dinner one year when I was alone for the holidays and introduced me to Yorkshire pudding, still one of my favorite dishes (though none has ever matched the pleasure of eating that first one from her oven).
Harriet apparently told her family that she didn't want a memorial, though from emails with her former students, I know that there might end up being *something* planned in Toronto.
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Cory Doctorow
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After all, memorials are for the living as much as for the dead. It's unlikely I'll be home for that one, but the best way to memorialize Harriet is in writing.
For Harriet, writing was a big, big church, and every kind of writing was worth serious attention. I always thought of the web as a very Wolffian innovation, because it exposed so many kinds of audiences to so many kinds of writers. There's Kate Wagner's acerbic Zillow annotations, of course, but also so much more.
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Cory Doctorow
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One of the web writers I've followed since the start is Kevin Kelly, who went from *The Whole Earth Review* to serving as *Wired*'s first executive editor. Over the years, Kevin has blazed new trails for those of us who write in public, publishing many seminal pieces online.
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Cory Doctorow
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But Kevin was and is a *print* guy, who has blazed new trails in self-publishing, producing books that are both brilliant *and* beautifully wrought artifacts, like his giant, three-volume set of photos of "Vanishing Asia":
vanishing.asia/the-making-of-v…
This week, Kelly published one of his famous soup-to-nuts guides to a subject: "Everything I Know about Self-Publishing":
kk.org/thetechnium/everything-…
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Everything I Know about Self-Publishing
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Cory Doctorow
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t's a long, thoughtful, and *very practical* guide that's full of advice on everything from printing to promo. I've self-published several volumes, and I learned a *lot*.
One very important writer who's trying something new this summer - to wonderful effect - is Hilary J Allen, a business law professor at American University. During the first cryptocurrency bubble, Allen wrote some of the sharpest critiques of fintech, dubbing it "Shadow Banking 2.0":
pluralistic.net/2022/03/02/sha…
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Pluralistic: 02 Mar 2022 – Pluralistic: Daily links from Cory Doctorow
pluralistic.netCory Doctorow
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Allen also coined the term "driverless finance," a devastatingly apt description of the crypto bro's desire for a financial system with no governance, which she expounded upon in a critical book:
driverlessfinancebook.com/
This summer, Allen has serialized "FinTech Dystopia," which she called "A summer beach read about Silicon Valley ruining things." Chapter 9 dropped this week, "Let’s Get Skeptical":
fintechdystopia.com/chapters/c…
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Driverless Finance
driverlessfinancebook.comCory Doctorow
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It's a tremendous read, and while it mostly concerns itself with summarizing her arguments against the claims of fintech boosters, there's an absolutely jaw-dropped section on Neom, the doomed Saudi megaproject to build a massive "linear city" in the desert:
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Cory Doctorow
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> More than 21,000 workers (primarily from India, Bangladesh, and Nepal) are reported to have died working on NEOM and related projects in Saudi Arabia since 2017, with more than 20,000 indigenous people reported to have been forcibly displaced to make room for the development.
Allen offers these statistics as part of her critique of the "Abundance agenda," which focuses on overregulation as the main impediment to a better world.
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Cory Doctorow
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Like Allen, I'm not afraid to criticize *bad* regulation, but also like Allen, I'm keenly aware of the terrible harms that arise out of a totally unregulated system.
The same goes for technology, of course. There's plenty of ways to use technology that is harmful, wasteful and/or cruel, but that isn't a brief *against technology itself* There are many ways that technology has been used (and can be used) to make things better.
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Cory Doctorow
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One of the pioneers of technology for good is Jim Fruchterman, founder of the venerable tech nonprofit Benetech, for which he was awarded a Macarthur "Genius" award. Fruchterman has just published his first book, with MIT Press, in which he sums up a lifetime's experience in finding ways to improve the world with technology. Appropriately enough, it's called *Technology For Good*:
mitpress.mit.edu/9780262050975…
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Book Details - MIT Press
The MIT Press, Massachusetts Institute of TechnologyCory Doctorow
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After all, technology is so marvelously flexible that there's always a countertechnology, for every abusive tech. Every 10-foot digital wall implies an 11-foot digital ladder. Last month, I wrote about Echelon, a company that makes digitally connected exercise bikes, who had pushed a mandatory update to their customers' bikes that took away functionality they got for free and sold it back to them in inferior form:
pluralistic.net/2025/07/26/man…
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Pluralistic: Iranian brickwork, arbitrated pillows, smothered comics, and aerogel desalination (26 Jul 2025) – Pluralistic: Daily links from Cory Doctorow
pluralistic.netCory Doctorow
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Repair hero Louis Rossman - who is running a new, direct action right to repair group named Fulu - offered a $20,000 bounty to anyone who could crack the firmware on an Echelon bike and create a disenshittified software stack that restored the original functionality:
youtube.com/watch?v=2zayHD4kfc…
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FULU Foundation offers $20,000 bounty to unbrick echelon bikes
YouTubeCory Doctorow
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In short order, app engineer Ricky Witherspoon, cracked it, and had a way to continue to use SyncSpin, his popular app for Echelon bikes, which was shut out by Echelon's enshittification. However, as Witherspoon told 404 Media's Jason Koebler, he won't release his code, not even for a $20,000 bounty, because doing so would make him liable to a *$500,000* fine, *and* a five-year prison sentence, under Section 1201 of the Digital Millennium Copyright Act:
404media.co/developer-unlocks-…
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404 Media
2025-08-27 20:22:43
Cory Doctorow
in reply to Cory Doctorow • • •Sensitive content
Fulu paid Witherspoon anyway (they're good eggs). Witherspoon told Koebler:
> For now it’s just about spreading awareness that this is possible, and that there’s another example of egregious behavior from a company like this […] if one day releasing this was made legal, I would absolutely open source this. I can legally talk about how I did this to a certain degree, and if someone else wants to do this, they can open source it if they want to.
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Cory Doctorow
in reply to Cory Doctorow • • •Sensitive content
Free/open source software is a powerful tonic against enshittification, and it has the alchemical property of transforming the products of bad companies into *good* utilities that everyone benefits from.
One example of this is Whisper, an open source audio transcription model released by Openai. Since Whisper's release, free software hackers have made steady - even remarkable - improvements to it.
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Cory Doctorow
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I discovered Whisper this summer, when I couldn't locate a quote I'd heard on a podcast that I wanted to reference in a column. I installed Whisper on my laptop and fed it the last 30+ hours of podcasts I'd listened to. An hour later, it had fully transcribed all of them, with timecode, and had put so little load on my laptop that the fan didn't even turn on. I was able to search all that text, locate the quote, and use the timecode to find the clip and check the transcription.
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Cory Doctorow
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Whisper has turned extremely accurate transcription into a utility, something that can just be added to any program or operating system for free. I think this is going to be quietly revolutionary, bringing full-text search and captioning to audio and video as something we can just take for granted.
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Cory Doctorow
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That's already happening! FFMpeg is the gold-standard free software tool for converting, encoding and re-encoding video, and now the latest version integrates Whisper, allowing FFMpeg to subtitle your videos on the fly:
theregister.com/2025/08/28/ffm…
Whisper is an example of the "residue" that will be left behind when the AI bubble pops. All bubbles pop, after all, but not all bubbles leave behind a useful residue.
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Whisper it: FFmpeg 8 can now subtitle your videos on the fly
Liam Proven (The Register)Cory Doctorow
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When crypto dies, its residue will be a few programmers who've developed secure coding habits in Rust, but besides that, all that will be left behind is terrible Austrian economics and worse monkey JPEGs:
pluralistic.net/2023/12/19/bub…
But the free/open source code generated by stupid and/or evil projects often lives on long after those projects are forgotten. And lots (most) of free/open code is written for *good* purposes.
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Pluralistic: What kind of bubble is AI? (19 Dec 2023) – Pluralistic: Daily links from Cory Doctorow
pluralistic.netCory Doctorow
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Take Madeline, a platform for tracking loans made by co-operatives, produced by the Seed Commons, which is now used by financial co-ops around the world, as they make "non-extractive investments in worker and community-owned businesses on the ground":
seedcommons.org/posts/digital-…
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Digital infrastructure for a non-extractive economy: The story of Madeline | Seed Commons
Seed Commons | A Community Wealth CooperativeCory Doctorow
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Madeline (and Seed Commons) are one of those bright lights that are easy to miss in these brutal and terrifying times. And if that's not enough, there's always booze. If you're thinking of drowning your sorrows, you could do worse than to pour your brown liquor out of a decanter shaped like a giant Atari CX-10 joystick:
atari.com/products/atari-joyst…
That's the kind of brand necrophilia that could really enhance a night's drinking.
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Atari Joystick Decanter Set
Atari®Cory Doctorow
in reply to Cory Doctorow • • •Sensitive content
The most enshittification-proof way to get the Enshittification audiobook, ebook and hardcover is to pre-order them on my Kickstarter! Help me do an end-run around the Amazon/Audible audiobook monopoly and disenshittify your audiobook experience in the process:
disenshittification.org
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Molly White
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Faraiwe
in reply to Cory Doctorow • • •naturally, this only works in that same ideal/purely theoretical sense (ask any carpenter or mechanic) in which all cows are orbs for Physicists. =)
It's not that Mathematicians don't have a sense of humor, it's just that most of it is not perceivable by humans, such as - say - that of Astrophysicists.
traverso
in reply to Cory Doctorow • • •Cory Doctorow reshared this.
Matt Diamond
in reply to Cory Doctorow • • •A small correction to this description— this new polyhedron is convex, not platonic. All platonics ARE Rupert; this new solid disproves the conjecture that all CONVEX 3d polyhedra are Rupert.
And I agree, Noperthedron is a great name for it. I wouldn’t have noticed the name if you hadn’t pointed it out.
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Paul Cantrell
in reply to Matt Diamond • • •A second correction (sorry):
Rupert’s property is that an identical cube can •pass through• the hole, not •fit inside• it.
(The latter would is trivially true if we read it as “at least some of it can fit inside the hole” — just remove any point on the surface — and would clearly be impossible if we read it as “fitting fully inside the hole” unless we allow the “hole” to consist of the entire polyhedron’s volume.)
The more formal definition of Rupert’s property is that there there are two different isometric 2D projections of a cube such that one of the resulting 2D shapes is a subset of the other.
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John Carlos Baez
in reply to Paul Cantrell • • •Paul Cantrell
in reply to John Carlos Baez • • •@johncarlosbaez
I’m not sure what “interior” means in a mathematical sense here. Can you clarify?
John Carlos Baez
in reply to Paul Cantrell • • •- a point 𝑥 is in the 'interior' of a subset S of the plane if for some number ε>0, every point that has distance < ε to x is in S.
If we drop my legalistic caveat, a the cube would obey Rupert's property simply because it's easy to find two different 2d projections of the cube that are both equal to each other: both a square, for example.
This caveat forces us to find one 2d projection that fits 'truly inside' another projection.
Paul Cantrell
in reply to John Carlos Baez • • •@johncarlosbaez
Ah, OK! The paper in question just defines it using a proper subset (definition 1) to rule out two projections with identical results:
arxiv.org/pdf/2508.18475
I wonder if there are shapes where your topological constraint rules something out, e.g. a shape where the only projection that satisfies the Rupert property touches the boundaries.
John Carlos Baez
in reply to Paul Cantrell • • •@inthehands - oh, my bad!
Then a round ball is Rupert by that paper's definition, but it's ruled out by my extra constraint.
(The hole you have to cut out of the ball, to fit an identical ball through, is the entire ball!)
But they were only talking about convex polyhedra, not a ball. I don't know if there are convex polyhedra ruled out by my extra constraint, that their paper would allow!
Paul Cantrell
in reply to John Carlos Baez • • •@johncarlosbaez
Re ball: I don’t think so? Entire ball is not a proper subset, right? (They say ⊂ and not ⊆.) Am I missing something?
Ballooniper 🎈🏳️⚧️
in reply to Paul Cantrell • • •John Carlos Baez
in reply to Ballooniper 🎈🏳️⚧️ • • •@eruonna - Thanks! Okay, so I wasn't dreaming after all when I said the paper says:
A (pointsymmetric) convex polytope has Rupert's property if one projection of it is a subset of the interior of some other projection.
Now, they use the symbol ⊂ , which should mean proper subset. But:
1) a lot of people use it to mean subset, and
2) one projection of a convex polytope is a subset of the interior of some other projection if and only if it is a PROPER subset of the interior of that other projection.
So we could use ⊆ and the meaning wouldn't change.
(A closed subset of a nonempty open subset of the plane must be a proper subset.)
@inthehands wrote: "I don’t think so? Entire ball is not a proper subset, right? (They say ⊂ and not ⊆.) Am I missing something?"
You're right, the entire ball is not a proper subset. So I was
... show more@eruonna - Thanks! Okay, so I wasn't dreaming after all when I said the paper says:
A (pointsymmetric) convex polytope has Rupert's property if one projection of it is a subset of the interior of some other projection.
Now, they use the symbol ⊂ , which should mean proper subset. But:
1) a lot of people use it to mean subset, and
2) one projection of a convex polytope is a subset of the interior of some other projection if and only if it is a PROPER subset of the interior of that other projection.
So we could use ⊆ and the meaning wouldn't change.
(A closed subset of a nonempty open subset of the plane must be a proper subset.)
@inthehands wrote: "I don’t think so? Entire ball is not a proper subset, right? (They say ⊂ and not ⊆.) Am I missing something?"
You're right, the entire ball is not a proper subset. So I was wrong about that.
We can use a plane to slice a small 'cap' off a round ball. Then one projection of this shape is a proper subset of another projection, but never a subset of the interior of that projection.
Paul Cantrell
in reply to John Carlos Baez • • •@johncarlosbaez @eruonna
It’s possible they might sharpen up these details in peer review. In any case, the alternative definitions do pose some interesting questions!
John Carlos Baez
in reply to Paul Cantrell • • •Paul Cantrell
in reply to John Carlos Baez • • •@johncarlosbaez @eruonna
Not for polyhedra, anyway!
(…through I’m pretty sure that proving even that rigorously requires more topology than I’ve got)
GhostOnTheHalfShell
in reply to Cory Doctorow • • •Radio Free Trumpistan
in reply to Cory Doctorow • •Oh good heavens, now we know: the Gallifreyans got their physics from Rupert. Who knew. Who knew?
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