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Reposted by χle Ormsby

Dave Richeson @divbyzero.bsky.social · 6h

New blog post! Through a sequence of images, I verify that the unknotting number of the connected sum of a (2,7) torus knot and its mirror is less than 6: I show that this first image is the connected sum, and after changing those crossings, it produces the unknot! divisbyzero.com/2025/10/08/t...

A drawing of the connected sum of a (2,7) torus knot and its mirror image (much modified).

An image of a crazy knot I claim is the unknot.

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χle Ormsby @motivickyle.bsky.social · 10h

The Active Calculus textbook just sent me down a fun rabbit hole.

Q: How do we know that the inverse to f(x) = x + sin(x) is not elementary?

A: Extended to the complex numbers, the inverse has infinitely many branch points!

Exercise 10 from https://activecalculus.org/single2e/sec-2-6-inverse.html.

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χle Ormsby @motivickyle.bsky.social · 10h

To be clear, this is a PDX post. Couch rhymes with hooch if you're talking about the street in NE Portland.

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χle Ormsby @motivickyle.bsky.social · 13h

Couch

Merriam-Webster @merriam-webster.com · 13h

What’s the word where you’re from that, when pronounced exactly as it looks, identifies a tourist immediately?

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χle Ormsby @motivickyle.bsky.social · 15h

If I were running an AI training company, I would probably try to name my company something that doesn't look like abbreviation of "Alignment Error".

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χle Ormsby @motivickyle.bsky.social · 15h

Hello? I'd like to report an attempted nerd-sniping by a targeted ad trying to pay me to teach algebraic topology to a neural net.

Targeted ad from reddit that says "If you can solve this, You belong at Alignerr. Earn up to $150/hr" and the problem is an octagon with sides identified in pairs and you're supposed to determine the genus of the associated surface.

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Reposted by χle Ormsby

subvariety sarah @scgriffith.bsky.social · 16h

the citation is these talk slides www.jaist.ac.jp/~bjorner/ae-..., which include the following horrible image

GCC, maple, mathematica, pari and mupad giving dramatically different answers to sin(10^22)

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χle Ormsby @motivickyle.bsky.social · 18h

Neat! But I’m wondering: What does “surface area” mean at this scale?

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Reposted by χle Ormsby

Carl Quintanilla @carlquintanilla.bsky.social · 22h

#WarRavagedPortland

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χle Ormsby @motivickyle.bsky.social · 1d

Excuse me. “Bongo Cat is the iconic, meow-singing cat that you will never forget after listening to one of her songs. Bongo Cat interprets current hits in her very special style and with enchanting animations.” www.kirine.me/meowing

KiRiNE - Meowing

Bongo Cat "Bongo Cat" is the iconic, meow-singing cat that you will never forget after listening to one of her songs. Bongo Cat interprets current hits in her very special style and with enchanting ...

www.kirine.me

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χle Ormsby @motivickyle.bsky.social · 1d

\qedsymbol 🧮

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χle Ormsby @motivickyle.bsky.social · 1d

I will not be taking questions regarding why I was listening to a Bongo Cat cover of Apt. at this time.

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χle Ormsby @motivickyle.bsky.social · 1d

Not sure what I expected when I pulled up the lyrics tab for a “Bongo Cat” cover of Apt. by ROSÉ and Bruno Mars.

Lyrics that just say “meow-meow” over and over.

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χle Ormsby @motivickyle.bsky.social · 1d

Morning moonset 🌕 🌲 🌞

Full moon setting at dawn over a redwood

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χle Ormsby @motivickyle.bsky.social · 2d

Calculus for Mathematicians! What a lovely little précis.

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χle Ormsby @motivickyle.bsky.social · 2d

Via a roundabout and unexpected path, I just encountered Carathéodory derivatives again, and I'm kind of shocked how easy the chain rule is via that definition. Do you know any references that develop basic calculus from that perspective?

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χle Ormsby @motivickyle.bsky.social · 2d

Me [having just bonked my head on a tree branch while hiking]: Ouch! Does my head look injured?

Spouse [zero hesitation]: Not on the outside.

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Reposted by χle Ormsby

Peter Kagey @peterkagey.com · 3d

I just re-designed my website away from Wordpress so that I could more easily embed 3D objects, Javascript, and more.

Check out my first blog post that takes advantage of these new features, based on a Bluesky post that I made back in May.

Pentagonal icositetrahedron puzzle

A puzzle on the faces of the pentagonal icositetrahedron with 3D models, STL files, photos, and video illustrations

peterkagey.com

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Reposted by χle Ormsby

Senator Ron Wyden @wyden.senate.gov · 3d

They’re using American tax dollars to fund infrastructure in Argentina because that’s where they’re all going to flee when we kick them out of office

Ryan Grim @ryangrim.bsky.social · 7d

After announcing a $20 billion bailout of Argentina, the White House now says it's pausing $18 billion in funding for NYC infrastructure projects

Russ Vought would love nothing more than to tear this country down to its studs

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χle Ormsby @motivickyle.bsky.social · 3d

Completely deranged. I love it.

χle Ormsby @motivickyle.bsky.social · 3d

This is why I'm teaching my 8yo that 5 factors as (2+i)(2-i).

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χle Ormsby @motivickyle.bsky.social · 3d

This is what the Buddha meant by the Middle Way (Madhyamāpratipada).

subvariety sarah @scgriffith.bsky.social · 4d

the truth is always in between the extremes. that is why mathematical objects should be indexed starting with 0.5

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χle Ormsby @motivickyle.bsky.social · 4d

Met some great dogs, but none were the right fit for us. Oregon Dog Rescue is a stone’s throw from the ICE protests and doing great work. www.oregondogrescue.org

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χle Ormsby @motivickyle.bsky.social · 4d

Adopted two hours before our appointment 😭

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χle Ormsby @motivickyle.bsky.social · 4d

Very NYT of the NYT to run a Red Scare article about Portland while we’re occupied by the federal government.

Alex Zielinski @alexzee.bsky.social · 4d

Not only does this story get a number of basic facts wrong, it doesn’t take time to actually explore why Portlanders elected these folks. Coming in with a pre-baked PDX story to fit a NYT narrative about NYC is harmful, especially at this moment.

What Happens When Socialists Are in Charge? Portland Offers a Glimpse.

www.nytimes.com

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