iiinova — where your digital self keeps evolving

Dirk Lorenz @dirque.bsky.social · 11h

I see - but clearing up who I follow seems like quite a challenge...

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Dirk Lorenz @dirque.bsky.social · 13h

I think I'll try again to build my feed, but thanks!

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Dirk Lorenz @dirque.bsky.social · 14h

Just created an account on mu - find me here: mu.social/profile/dirq...

mu.social

@dirque.eurosky.social

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Dirk Lorenz @dirque.bsky.social · 16h

All well-posed problems are alike; each ill-posed problem is ill-posed in its own way.

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Dirk Lorenz @dirque.bsky.social · 23/09/2026

Had a hard time grading seminar reports and presentations recently (you know, AI). Idea for next seminar: Give students papers I did not read (but would like to). They need to explain the paper to me (orally and in writing) and the grade is determined only by how good I understand.

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Dirk Lorenz @dirque.bsky.social · 23/09/2026

Signs that academia may be for you: * eduroam works on the first try * you get your travel reimbursement without having to email anyone twice * you understand your institution’s course management system

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Dirk Lorenz @dirque.bsky.social · 23/09/2026

Material decomposition with multispectral computed tomography still feels underresearched mathematically!Here is what Jürgen Jeschke and I came up with to better understand what is going on. arxiv.org/abs/2609.25926

arxiv.org

Enhanced attenuation modelling for multispectral computed tomography

We revisit the modelling of the material decomposition problem in multispectral computed tomography and propose to leverage the known absorption spectra of different materials. With this we both deriv...

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Dirk Lorenz @dirque.bsky.social · 20/07/2026

That's what you get when you submit to the "top tier" journals

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Reposted by Dirk Lorenz

Guillaume @guillaume-garrigos.com · 20/07/2026

As I am preparing my calculus notes for next year, the resolution of the jacobian conjecture comes at the perfect time! Today I've learned a few things surrounding this result, which i'll gather in a thread 1/n

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Dirk Lorenz @dirque.bsky.social · 08/06/2026

I remember playing Civ 1 with somebody and we needed quite some time to figure out that Russian and Chinese looked exactly the same to him...

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Dirk Lorenz @dirque.bsky.social · 08/06/2026

The perception of color is by no means equal, especially in the green/blue area. I meet people with other color perception than myself much more often than I think.

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Dirk Lorenz @dirque.bsky.social · 06/06/2026

The two couples that I know that actually had to marry for this very reason were no mathematicians. It was more of a Catholic thing

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Dirk Lorenz @dirque.bsky.social · 06/06/2026

Some of us even minmaxmaxxing

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Dirk Lorenz @dirque.bsky.social · 06/06/2026

Rebrand optimization as argmaxxing

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Reposted by Dirk Lorenz

Sophie Huiberts @sophie.huiberts.me · 05/06/2026

George Dantzig died in 2005. Does anyone have any color photographs of him?

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Dirk Lorenz @dirque.bsky.social · 05/06/2026

Maybe and thanks for raising the other points! Still interesting that "computation" was and still is considered inferior to proving. Also I think "Writing instructions for a machine to produce a proof" may still be a good job

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Dirk Lorenz @dirque.bsky.social · 05/06/2026

Indeed! Also interesting that there was no urge to emphasize *human* computation or *human* calculation when it became possible that non-humans do these (or was there?)

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Reposted by Dirk Lorenz

Société Mathématique de France @socmathfrance.bsky.social · 05/06/2026

The International Centre for Mathematical Sciences (ICMS, Edinburgh) is looking for a new Director. Application deadline is July 15. Please share this information with anyone who might be interested. icms.ac.uk/icms-seeks-n...

icms.ac.uk

ICMS seeks new Director - ICMS

ICMS seeks a new director as the tenure of our current Director, Minhyong Kim, comes to an end this summer.

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Dirk Lorenz @dirque.bsky.social · 03/06/2026

Every optimization problem is linear if you lift enough

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Dirk Lorenz @dirque.bsky.social · 02/06/2026

I noticed that LLMs already affect student presentations a lot, but now at #SIAMOP26 I realize that also here, people use ChatGPT et al. to produce their slides (at least, that's the obvious explanation for all the "Why this matters" boxes I see on slides...)

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Dirk Lorenz @dirque.bsky.social · 02/06/2026

That's a hell of a venue for a plenary talk here at #SIAMOP26

Photo of a very fancy old lecture hall from University of Edinburgh

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Dirk Lorenz @dirque.bsky.social · 06/05/2026

No translation invariant measure on the power set of the reels?

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Dirk Lorenz @dirque.bsky.social · 24/04/2026

But also the existence of InfoPeace, DataPeace, KnowledgePeace, and WisdowPeace!

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Dirk Lorenz @dirque.bsky.social · 15/04/2026

The exponential function has the remarkable property that it is the unique function f that satisfies the differential equation f'(x) = exp(x) with initial value f(0)=1.

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Dirk Lorenz @dirque.bsky.social · 21/03/2026

Everybody is dead. Chuck Norris is still alive.

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Dirk Lorenz @dirque.bsky.social · 16/03/2026

Well, it's within Germany so I travel by train and that's as safe as the trunk of any car I'd say

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Dirk Lorenz @dirque.bsky.social · 16/03/2026

Modern technology makes conference evenings in the hotel much more enjoyable!

An electric guitar with a headphone amp in a hotel chair

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Dirk Lorenz @dirque.bsky.social · 07/03/2026

I also needed assistance by some Minecraft-savvy guy. Unfortunately I don't remember how that worked

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Dirk Lorenz @dirque.bsky.social · 07/03/2026

Omg my daughter just passed the reverse Turing! But now she's stuck at the chess level

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Dirk Lorenz @dirque.bsky.social · 07/03/2026

Or was it "yourself" with some glitter around?

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Dirk Lorenz @dirque.bsky.social · 07/03/2026

I think we passed by just writing "self"

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Dirk Lorenz @dirque.bsky.social · 07/03/2026

Darauf hat man als Prof eigentlich gar keinen Einfluss - das entscheidet die Personalabteilung. Manchmal habe ich versucht, eine höhere Einstufung zu erreichen, aber da ist selten was zu machen

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Dirk Lorenz @dirque.bsky.social · 07/03/2026

19 to the right and 10 down

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Dirk Lorenz @dirque.bsky.social · 07/03/2026

I tried again and finally got to level 42! It's a reverse Turing and it really feels like it's not meant to be passed

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Dirk Lorenz @dirque.bsky.social · 07/03/2026

Das ja. Ich dachte es ginge darum, dass Profs Vorteile dadurch haben, dass nur befristet anstellen.

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Dirk Lorenz @dirque.bsky.social · 07/03/2026

Als Prof sehe ich für mich auch keine Vorteile darin, dass alle Verträge befristet sein müssen. Befristetes Projektgeld ist eine Sache, aber dass auch Uni-Geld nur für befristete Verträge geht ärgert auch mich.

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Dirk Lorenz @dirque.bsky.social · 07/03/2026

Prove that you are human - once and for all I can't get past level 4 🤖😬 neal.fun/not-a-robot/

neal.fun

I'm Not a Robot

Prove your humanity once and for all

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Reposted by Dirk Lorenz

ISMP 2027 – Amsterdam @ismp2027.bsky.social · 27/02/2026

📢 #ISMP2027 comes to Amsterdam! The 26th International Symposium on Mathematical Programming will be held July 25–30, 2027. Join researchers from around the world to discuss advances, challenges, and opportunities in the theory and practice of mathematical optimization. 🔗 ismp2027.mathopt.nl #MOS

ismp2027.mathopt.nl

The 26th International Symposium on Mathematical Programming will be held in Amsterdam, The Netherlands, from July 25th through July 30th, 2027. The event is the symposium of the Mathematical Optimization Society (MOS).

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Dirk Lorenz @dirque.bsky.social · 02/03/2026

Am I right that a function that is not increasing and also not decreasing is in fact just creasing?

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Dirk Lorenz @dirque.bsky.social · 27/02/2026

After reading on MPS files, I say that there are several things about them that are misleading! (They don't know if the problem is about maximizing or minimizing! If you specify an upper bound and no lower bound is the lower bound of zero still used? What if I specify a lower bound of -1?)

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Dirk Lorenz @dirque.bsky.social · 27/02/2026

I for one don't know what an MPS file even is. In a package like scipy that is for a general audience in scientific computing it is definitely confusing.

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Dirk Lorenz @dirque.bsky.social · 27/02/2026

Most people in everyday life wouldn't call a straight line a convex function (most people wouldn't speak about functions anyway, but well...). (Sorry for reviving this, just appeared in my timeline again)

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Dirk Lorenz @dirque.bsky.social · 26/02/2026

And bound=none makes this abundantly clear - got it!

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Dirk Lorenz @dirque.bsky.social · 26/02/2026

So you tell me that when I call scipy's linprog with bounds=none, it uses a lower bound of zero?! Yeah, that makes a lot of sense #scipy!

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Reposted by Dirk Lorenz

David K Butler @davidkbutler.bsky.social · 20/02/2026

I submit the following for the fifth derivative.

The letter y with a superscript that is four vertical tally marks with a fifth diagonal tally mark across them.

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