Dirk Lorenz
@dirque.bsky.social
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.
Reposted by Dirk Lorenz
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 💛✨
January 20, 2026 at 10:48 AM
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 💛✨
Universidad Técnica Federico Santa María in Valparaiso has a quite iconic campus tbh
January 19, 2026 at 4:44 PM
Universidad Técnica Federico Santa María in Valparaiso has a quite iconic campus tbh
These tiles don't cease to amaze - with hexagonal holes you get a lot of symmetry!
December 31, 2025 at 10:21 AM
These tiles don't cease to amaze - with hexagonal holes you get a lot of symmetry!
December 28, 2025 at 6:50 PM
Reposted by Dirk Lorenz
![Comic. [Banner: Mathematical Society: 2025 Meeting.] PERSON 1 with bun: Any other new developments from the year to cover before we wrap? PERSON 2: Oh, the teens picked a new funny number. PERSON 3 with short hair: Aww, I’m glad to hear they’re still doing that. PERSON 4 with ponytail: I’ll add it to the list. [List: 23 (skidoo!; 42; 69; 420; 1,337; 58,008; [circled]: 67]](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:cz73r7iyiqn26upot4jtjdhk/bafkreig43e2u4zzpifhq6fbf2iwplmva2lt5rokfg5uws5dysbe55up6wa@jpeg)
December 26, 2025 at 10:44 PM
December 27, 2025 at 5:49 PM
Reposted by Dirk Lorenz
Does anyone have a links to good writing on what "trivial" means in mathematics? How we might define that type of thing?
I get why people don't like the term, I want to help students seek out trivial examples/results as a way of getting familiar with whatever property we're working with.
#MathSky
I get why people don't like the term, I want to help students seek out trivial examples/results as a way of getting familiar with whatever property we're working with.
#MathSky
December 16, 2025 at 3:40 PM
Does anyone have a links to good writing on what "trivial" means in mathematics? How we might define that type of thing?
I get why people don't like the term, I want to help students seek out trivial examples/results as a way of getting familiar with whatever property we're working with.
#MathSky
I get why people don't like the term, I want to help students seek out trivial examples/results as a way of getting familiar with whatever property we're working with.
#MathSky
Reposted by Dirk Lorenz
New paper out! Together with my postdoc advisors @esoubies.bsky.social and Cédric Févotte :)
We study the optimization landscape of L0-Bregman relaxations, which naturally arise when one optimizes non-quadratic fidelity terms coupled with the L0-norm.
1/n
We study the optimization landscape of L0-Bregman relaxations, which naturally arise when one optimizes non-quadratic fidelity terms coupled with the L0-norm.
1/n
Jonathan Chirinos-Rodriguez, C\'edric F\'evotte, Emmanuel Soubies
Optimization landscape of $\ell_0$-Bregman relaxations
https://arxiv.org/abs/2511.12157
Optimization landscape of $\ell_0$-Bregman relaxations
https://arxiv.org/abs/2511.12157
November 20, 2025 at 8:45 PM
New paper out! Together with my postdoc advisors @esoubies.bsky.social and Cédric Févotte :)
We study the optimization landscape of L0-Bregman relaxations, which naturally arise when one optimizes non-quadratic fidelity terms coupled with the L0-norm.
1/n
We study the optimization landscape of L0-Bregman relaxations, which naturally arise when one optimizes non-quadratic fidelity terms coupled with the L0-norm.
1/n
New on arXiv: Why noise matters in learned regularization!
Data-driven regularizers fail without noise structure. 🎯
Tikhonov, Lavrentiev, quadratic — not equal under non-white noise.
🤫 Spoiler: Optimal reconstruction needs proper noise modeling.
👉 Regularizer choice = structure and noise.
Data-driven regularizers fail without noise structure. 🎯
Tikhonov, Lavrentiev, quadratic — not equal under non-white noise.
🤫 Spoiler: Optimal reconstruction needs proper noise modeling.
👉 Regularizer choice = structure and noise.
Sebastian Banert, Christoph Brauer, Dirk Lorenz, Lionel Tondji
Why the noise model matters: A performance gap in learned regularization
https://arxiv.org/abs/2510.12521
Why the noise model matters: A performance gap in learned regularization
https://arxiv.org/abs/2510.12521
October 15, 2025 at 6:40 AM
New on arXiv: Why noise matters in learned regularization!
Data-driven regularizers fail without noise structure. 🎯
Tikhonov, Lavrentiev, quadratic — not equal under non-white noise.
🤫 Spoiler: Optimal reconstruction needs proper noise modeling.
👉 Regularizer choice = structure and noise.
Data-driven regularizers fail without noise structure. 🎯
Tikhonov, Lavrentiev, quadratic — not equal under non-white noise.
🤫 Spoiler: Optimal reconstruction needs proper noise modeling.
👉 Regularizer choice = structure and noise.
Reposted by Dirk Lorenz
What does it mean to do mathematics?
Read my personal answer here:
web.mathi.uni-heidelberg.de/content/uplo...
#mathsky #math #question
Read my personal answer here:
web.mathi.uni-heidelberg.de/content/uplo...
#mathsky #math #question
web.mathi.uni-heidelberg.de
September 19, 2025 at 2:24 PM
What does it mean to do mathematics?
Read my personal answer here:
web.mathi.uni-heidelberg.de/content/uplo...
#mathsky #math #question
Read my personal answer here:
web.mathi.uni-heidelberg.de/content/uplo...
#mathsky #math #question
So you agree that the sine function is not decreasing, but you won't say that it's non-decreasing? But alas math has such a precise language! 🧮
Why do we use "non-decreasing" as a synonym for increasing? The negation is confusing. E.g., the sine function is not decreasing. Is the distinction between strictly and non-strictly increasing meaningful?
September 11, 2025 at 8:05 PM
So you agree that the sine function is not decreasing, but you won't say that it's non-decreasing? But alas math has such a precise language! 🧮
Reposted by Dirk Lorenz
Ta daaa! I give you the Lorentz Attractor thanks to the free pattern from #ThreadedTheorems and also @samjshah.bsky.social whose posted work I admired.
#StemBroidery #MathArt #MathSky
#StemBroidery #MathArt #MathSky
September 6, 2025 at 10:08 PM
Ta daaa! I give you the Lorentz Attractor thanks to the free pattern from #ThreadedTheorems and also @samjshah.bsky.social whose posted work I admired.
#StemBroidery #MathArt #MathSky
#StemBroidery #MathArt #MathSky
Reposted by Dirk Lorenz
Join us for a panel on “Careers in Mathematics of Data Science” tomorrow morning!
Save the Date!
The SIAM Activity Group on Data Science (SIAG/DATA) invites you to join us for a panel on the topic:
Careers in Mathematics of Data Science
Tuesday, August 12, 2025 | 9:00 AM PT | Zoom Webinar
Panelists: Marta D’Elia, Elizabeth Newman, David Uminsky
The SIAM Activity Group on Data Science (SIAG/DATA) invites you to join us for a panel on the topic:
Careers in Mathematics of Data Science
Tuesday, August 12, 2025 | 9:00 AM PT | Zoom Webinar
Panelists: Marta D’Elia, Elizabeth Newman, David Uminsky
Welcome! You are invited to join a webinar: Webinar on the Mathematics of Data Science. After registering, you will receive a confirmation email about joining the webinar.
Panel: Careers in Mathematics of Data Science
Join us for an engaging panel discussion on careers in the mathematics of data science, featuring experts from academia, industry, and national labs. Thi...
siam.zoom.us
August 11, 2025 at 2:50 PM
Join us for a panel on “Careers in Mathematics of Data Science” tomorrow morning!
Reposted by Dirk Lorenz
Our latest WebMDS webinar was a blast!
Check out our panel discussion of "Careers in Mathematics of Data Science" on youtube:
youtu.be/qdlJJLT4ddQ?...
Check out our panel discussion of "Careers in Mathematics of Data Science" on youtube:
youtu.be/qdlJJLT4ddQ?...
Panel: Careers in Mathematics of Data Science
YouTube video by Society for Industrial and Applied Mathematics (SIAM)
youtu.be
August 15, 2025 at 1:13 PM
Our latest WebMDS webinar was a blast!
Check out our panel discussion of "Careers in Mathematics of Data Science" on youtube:
youtu.be/qdlJJLT4ddQ?...
Check out our panel discussion of "Careers in Mathematics of Data Science" on youtube:
youtu.be/qdlJJLT4ddQ?...
Reposted by Dirk Lorenz
Register at siam.zoom.us/webinar/regi...
Welcome! You are invited to join a webinar: Webinar on the Mathematics of Data Science. After registering, you will receive a confirmation email about joining the webinar.
Panel: Careers in Mathematics of Data Science
Join us for an engaging panel discussion on careers in the mathematics of data science, featuring experts from academia, industry, and national labs. Thi...
siam.zoom.us
August 1, 2025 at 8:38 PM
Register at siam.zoom.us/webinar/regi...
Reposted by Dirk Lorenz
Save the Date!
The SIAM Activity Group on Data Science (SIAG/DATA) invites you to join us for a panel on the topic:
Careers in Mathematics of Data Science
Tuesday, August 12, 2025 | 9:00 AM PT | Zoom Webinar
Panelists: Marta D’Elia, Elizabeth Newman, David Uminsky
The SIAM Activity Group on Data Science (SIAG/DATA) invites you to join us for a panel on the topic:
Careers in Mathematics of Data Science
Tuesday, August 12, 2025 | 9:00 AM PT | Zoom Webinar
Panelists: Marta D’Elia, Elizabeth Newman, David Uminsky
Welcome! You are invited to join a webinar: Webinar on the Mathematics of Data Science. After registering, you will receive a confirmation email about joining the webinar.
Panel: Careers in Mathematics of Data Science
Join us for an engaging panel discussion on careers in the mathematics of data science, featuring experts from academia, industry, and national labs. Thi...
siam.zoom.us
August 1, 2025 at 8:38 PM
Save the Date!
The SIAM Activity Group on Data Science (SIAG/DATA) invites you to join us for a panel on the topic:
Careers in Mathematics of Data Science
Tuesday, August 12, 2025 | 9:00 AM PT | Zoom Webinar
Panelists: Marta D’Elia, Elizabeth Newman, David Uminsky
The SIAM Activity Group on Data Science (SIAG/DATA) invites you to join us for a panel on the topic:
Careers in Mathematics of Data Science
Tuesday, August 12, 2025 | 9:00 AM PT | Zoom Webinar
Panelists: Marta D’Elia, Elizabeth Newman, David Uminsky
Reposted by Dirk Lorenz
I've invented a simple, lovely math puzzle I expect every AI fails:
Suppose you're a mathematical sailor at sea on a boat that has a perfectly cylindrical hole in the floor. All you brought is a collection of every p norm ball except p=2 (drat!). What do you do to cork the hole and save yourself?
Suppose you're a mathematical sailor at sea on a boat that has a perfectly cylindrical hole in the floor. All you brought is a collection of every p norm ball except p=2 (drat!). What do you do to cork the hole and save yourself?
August 4, 2025 at 11:57 PM
I've invented a simple, lovely math puzzle I expect every AI fails:
Suppose you're a mathematical sailor at sea on a boat that has a perfectly cylindrical hole in the floor. All you brought is a collection of every p norm ball except p=2 (drat!). What do you do to cork the hole and save yourself?
Suppose you're a mathematical sailor at sea on a boat that has a perfectly cylindrical hole in the floor. All you brought is a collection of every p norm ball except p=2 (drat!). What do you do to cork the hole and save yourself?
A: A mathematical statement/concept makes intuitive sense.
B: There is a sound framework where a mathematical statement/concept can be proven/defined.
I tend to believe that
A ⇒ B,
but not vice versa.
(Thinking about Dirac's delta and the Banach-Tarski paradox, for example.)
#🧮
B: There is a sound framework where a mathematical statement/concept can be proven/defined.
I tend to believe that
A ⇒ B,
but not vice versa.
(Thinking about Dirac's delta and the Banach-Tarski paradox, for example.)
#🧮
July 7, 2025 at 8:56 AM
A: A mathematical statement/concept makes intuitive sense.
B: There is a sound framework where a mathematical statement/concept can be proven/defined.
I tend to believe that
A ⇒ B,
but not vice versa.
(Thinking about Dirac's delta and the Banach-Tarski paradox, for example.)
#🧮
B: There is a sound framework where a mathematical statement/concept can be proven/defined.
I tend to believe that
A ⇒ B,
but not vice versa.
(Thinking about Dirac's delta and the Banach-Tarski paradox, for example.)
#🧮
I still did not subscribe to d(Amazon)/dx…
In Leibniz notation, his name is d(Optimus)/dx.
June 25, 2025 at 8:00 PM
I still did not subscribe to d(Amazon)/dx…
Reposted by Dirk Lorenz
Die Frage P=NP? ist eines der Milleniumsprobleme und somit lohnenswertes Ziel für Hobby- und Profimathematiker:innen.
www.claymath.org/millennium/p...
🧵
www.claymath.org/millennium/p...
🧵
P vs NP - Clay Mathematics Institute
If it is easy to check that a solution to a problem is correct, is it also easy to solve the problem? This is the essence of the P vs NP question. Typical of the NP problems is that of the Hamiltonian...
www.claymath.org
June 19, 2025 at 7:13 PM
Die Frage P=NP? ist eines der Milleniumsprobleme und somit lohnenswertes Ziel für Hobby- und Profimathematiker:innen.
www.claymath.org/millennium/p...
🧵
www.claymath.org/millennium/p...
🧵
I sample points uniformly on the sphere and then look at them on a map (in longitude and z-coordinate).
STILL UNIFORMLY DISTRIBUTED! 🤯
(Quite a nice fact that is special to three dimensions: Each coordinate of a random vector uniformly on the uni sphere is uniform in [-1,1].)
#🧮
STILL UNIFORMLY DISTRIBUTED! 🤯
(Quite a nice fact that is special to three dimensions: Each coordinate of a random vector uniformly on the uni sphere is uniform in [-1,1].)
#🧮
June 19, 2025 at 2:11 PM
I sample points uniformly on the sphere and then look at them on a map (in longitude and z-coordinate).
STILL UNIFORMLY DISTRIBUTED! 🤯
(Quite a nice fact that is special to three dimensions: Each coordinate of a random vector uniformly on the uni sphere is uniform in [-1,1].)
#🧮
STILL UNIFORMLY DISTRIBUTED! 🤯
(Quite a nice fact that is special to three dimensions: Each coordinate of a random vector uniformly on the uni sphere is uniform in [-1,1].)
#🧮
The recording of the @siagdata.bsky.social webinar "Teaching the mathematics of data science" is online!
youtu.be/nynELwnA8ow?...
youtu.be/nynELwnA8ow?...
Teaching the Mathematics of Data Science | Expert Panel Discussion
YouTube video by Society for Industrial and Applied Mathematics (SIAM)
youtu.be
June 13, 2025 at 9:54 PM
The recording of the @siagdata.bsky.social webinar "Teaching the mathematics of data science" is online!
youtu.be/nynELwnA8ow?...
youtu.be/nynELwnA8ow?...