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Dirk Lorenz

@dirque

Doing mathematics, also as a job. Now at Uni Bremen, was at TU Braunschweig. Only here for the math. Optimization, inverse problems, imaging, learning - stuff like that.

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Latest posts by Dirk Lorenz @dirque

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

07.03.2026 22:24 πŸ‘ 1 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

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

07.03.2026 22:23 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

Oha, das ist ΓΌbel

07.03.2026 22:22 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

Or was it "yourself" with some glitter around?

07.03.2026 20:39 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

I think we passed by just writing "self"

07.03.2026 20:36 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

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

07.03.2026 20:35 πŸ‘ 1 πŸ” 0 πŸ’¬ 2 πŸ“Œ 0

19 to the right and 10 down

07.03.2026 20:33 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

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

07.03.2026 20:32 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

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

07.03.2026 14:53 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

Als Prof sehe ich fΓΌr mich auch keine Vorteile darin, dass alle VertrΓ€ge befristet sein mΓΌssen. Befristetes Projektgeld ist eine Sache, aber dass auch Uni-Geld nur fΓΌr befristete VertrΓ€ge geht Γ€rgert auch mich.

07.03.2026 13:39 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
Preview
I'm Not a Robot Prove your humanity once and for all

Prove that you are human - once and for all

I can't get past level 4 πŸ€–πŸ˜¬

neal.fun/not-a-robot/

07.03.2026 13:35 πŸ‘ 6 πŸ” 0 πŸ’¬ 5 πŸ“Œ 0
Preview
a man is screaming with the words " unlimited power " behind him ALT: a man is screaming with the words " unlimited power " behind him

Chebyshev discovering his polynomials

04.03.2026 08:52 πŸ‘ 2 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0
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).

πŸ“’ #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.

πŸ”— ismp2027.mathopt.nl
#MOS

27.02.2026 08:03 πŸ‘ 25 πŸ” 8 πŸ’¬ 1 πŸ“Œ 2

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

02.03.2026 11:19 πŸ‘ 5 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

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?)

27.02.2026 15:35 πŸ‘ 1 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

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.

27.02.2026 15:29 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

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)

27.02.2026 05:27 πŸ‘ 3 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

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

26.02.2026 13:39 πŸ‘ 2 πŸ” 0 πŸ’¬ 2 πŸ“Œ 0

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!

26.02.2026 08:58 πŸ‘ 0 πŸ” 0 πŸ’¬ 2 πŸ“Œ 0
The letter y with a superscript that is four vertical tally marks with a fifth diagonal tally mark across them.

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

I submit the following for the fifth derivative.

20.02.2026 22:24 πŸ‘ 27 πŸ” 5 πŸ’¬ 2 πŸ“Œ 0
The potato meme: A picture of a baked potato with the text "Let the potato rest for five minutes"

The potato meme: A picture of a baked potato with the text "Let the potato rest for five minutes"

23.01.2026 21:03 πŸ‘ 1 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

"me rest for a little longer" maybe?

23.01.2026 21:00 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

Curious! Could you elaborate a bit on the way Sturmfels does math collaborations?

21.01.2026 15:18 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

Truly an outstanding achievement!

20.01.2026 11:58 πŸ‘ 4 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0
A dark blue celebratory graphic marking the 5-year anniversary of Her Maths Story. The HMS logo appears at the top. Large white text reads β€œ5 years” in the centre, surrounded by yellow star shapes. Additional text highlights milestones: 99 contributors, 200K website visitors, 194 countries reached via the website, and 4.9K followers across social media platforms.

A dark blue celebratory graphic marking the 5-year anniversary of Her Maths Story. The HMS logo appears at the top. Large white text reads β€œ5 years” in the centre, surrounded by yellow star shapes. Additional text highlights milestones: 99 contributors, 200K website visitors, 194 countries reached via the website, and 4.9K followers across social media platforms.

5 years ago today, Her Maths Story went live with our 1st story. What started as a small idea has grown into a global, supportive community celebrating #WomenInMaths. We’re deeply grateful to everyone who has shared, read, supported & believed in this journey. Here’s to the stories still to come πŸ’›βœ¨

20.01.2026 10:48 πŸ‘ 8 πŸ” 5 πŸ’¬ 1 πŸ“Œ 0

Is this even possible administration-wise? Where I am the administration needs at least six weeks between agreement and signature of the contract...

19.01.2026 18:18 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0
Post image Post image Post image

Universidad TΓ©cnica Federico Santa MarΓ­a in Valparaiso has a quite iconic campus tbh

19.01.2026 16:44 πŸ‘ 6 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

In hindsight: The chance that I learned that view some time in the past is fairly high. But when I read that post, it felt like learning something new!

18.01.2026 20:29 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

I've been doing math for some decades now and I never realized until today that the number to arrange n things is n! because it is n times 'number of ways to arrange n-1 things', since there are n places where to put it.

Only thought about it as "n places for the first thing, n-1 for the second…"

18.01.2026 15:00 πŸ‘ 2 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
Another periodic pattern with holes made of aperiodic tiles

Another periodic pattern with holes made of aperiodic tiles

These tiles don't cease to amaze - with hexagonal holes you get a lot of symmetry!

31.12.2025 10:21 πŸ‘ 4 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0