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Seth Axen 🪓

@sethaxen.com

2.7K followers 360 following 170 posts

Empowering scientists with machine learning @mlcolab.org. Sometimes #Bayesian. Usually #FOSS. Preferably in #JuliaLang. Expat: 🇺🇸 ➡️ 🇩🇪 💼 On the job market (remote/Stuttgart area) sethaxen.com

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Seth Axen 🪓 @sethaxen.com · Nov 18

Quick intro 👋! I help scientists use ML in their research. My background is in structural biology, but I now mostly post about FOSS topics. I've worked on tools for manifolds and autodiff, but these days I mostly focus on tools for Bayesian analysis, e.g. ArviZ. In my free time, I powerlift.

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Seth Axen 🪓 @sethaxen.com · 5d

"Matlab is the Visual Basic 6 of technical computing." #HeardAtJuliaCon #JuliaCon #JuliaLang

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Seth Axen 🪓 @sethaxen.com · 6d

"I'm sure I don't have to tell you that #JuliaLang is awesome and Matlab is not" #HeardAtJuliaCon #JuliaCon

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Reposted by Seth Axen 🪓

MC Stan @mc-stan.org · 21d

MC Stan is here! Follow for the latest Stan news, and tag if you want us to repost your posts about new papers, packages, courses, etc. about Stan

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Reposted by Seth Axen 🪓

sbi - Simulation-based inference @sbi-devs.bsky.social · 29d

From hackathon to release: sbi v0.25 is here! 🎉

What happens when dozens of SBI researchers and practitioners collaborate for a week? New inference methods, new documentation, lots of new embedding networks, a bridge to pyro and a bridge between flow matching and score-based methods 🤯

1/7 🧵

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Reposted by Seth Axen 🪓

Charles Margossian @charlesm993.bsky.social · 29d

My paper with Loucas Pillaud-Vivien and Lawrence Saul, “Variational Inference for Uncertainty Quantification: An Analysis of Trade-offs”, has been accepted for publication in the Journal of Machine Learning Research.

📃 arxiv.org/abs/2403.13748

🧵 1/

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Seth Axen 🪓 @sethaxen.com · 29d

QED

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Seth Axen 🪓 @sethaxen.com · Sep 8

I think he was counting the donuts

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Seth Axen 🪓 @sethaxen.com · Sep 8

Working from home and overhearing my 7-year-old trying to explain "countable infinity" to my partner using donuts.

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Reposted by Seth Axen 🪓

Jan Boelts @janboelts.bsky.social · Aug 18

Fun read of their amazing contributions to the SBI hackathon! 🥐
The SBI-Pyro bridge that @sethaxen.com built has a lot of potential I believe. I'll actually be presenting this work at @euroscipy.bsky.social this Wednesday - excited to share this with a broader audience.
euroscipy.org/talks/KCYYTF/

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Reposted by Seth Axen 🪓

Aki Vehtari @avehtari.bsky.social · Aug 2

All three books I've co-authored are freely available online for non-commercial use:

- #Bayesian Data Analysis, 3rd ed (aka BDA3) at stat.columbia.edu/~gelman/book/

- #Regression and Other Stories at avehtari.github.io/ROS-Examples/

- Active Statistics at avehtari.github.io/ActiveStatis...

The cover of Bayesian Data Analysis book

The cover of Regression and Other Stories book

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Seth Axen 🪓 @sethaxen.com · Aug 11

Pro-tip: don't be the poor sod that adds a daily cron trigger to a GitHub Actions workflow that often fails. Long after you've left the project, you will get *daily* failure notifications, and the only way out is to trick some other poor sod into editing the workflow. docs.github.com/en/actions/c...

Seth Axen 🪓 @sethaxen.com · Aug 11

I have a scheduling conflict with PyData but otherwise plan to do just this. Hope to see you there!

Seth Axen 🪓 @sethaxen.com · Aug 8

It's tempting to build one's intuition for statistics on arbitrary manifolds using simple manifolds like spheres or simplices. But to these manifolds, conditioning and restricting *are* the same thing. The authors show that on even an ellipse the two can give wildly different results.

Seth Axen 🪓 @sethaxen.com · Aug 8

Like the authors, I also found this result disturbing.

The crux is that *conditioning* a distribution to lie on a manifold is *not* in general the same thing as *restricting* the distribution to the manifold (i.e. constraining the support and re-normalizing).

arXiv math.ST Statistics Theory @mathst-bot.bsky.social · Aug 4

Natha\"el Da Costa, Marvin Pf\"ortner, Jon Cockayne: Constructive Disintegration and Conditional Modes https://arxiv.org/abs/2508.00617 https://arxiv.org/pdf/2508.00617 https://arxiv.org/html/2508.00617

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Seth Axen 🪓 @sethaxen.com · Aug 8

For the Bayesians, it's the Monte Hall problem.

Randall Munroe @xkcd.com · Aug 8

Snake-in-the-Box Problem

xkcd.com/3125/

Comic. A snake slithers around a hypercube. No two non-consecutive parts of its coils can be on adjacent corners. [Three small 4-dimensional hypercubes showing disallowed options with one large cube with snake wrapped around it. Dimensions = 4. Max Length - 7.] Snake(N) = Longest snake that can fit in an n-dimensional hypercube. Snake(N=1, 2, 3…8) = 1, 2, 4, 7, 13, 26, 50, 98. Snake(N>8) = UNSOLVED. [caption] It turns out every scientific field has a key thought experiment that involves putting a cute animal in a weird box for no reason. So far, quantum mechanics and graph theory have found theirs, but most other fields are still working on it.

Seth Axen 🪓 @sethaxen.com · Aug 5

I've also been rocking a @frame.work laptop for the last ~4 years and have been similarly pleased with how straightforward it has been to fix problems as they've come up without wasting time and money on newer but only marginally better devices.

Seth Axen 🪓 @sethaxen.com · Aug 5

Finally, a part of my Fairphone 5 stopped working. For any other phone, I'd be dropping >500€ right now to replace it with a marginally better brand new phone that would last me just 2-3 years. Instead, I paid 41€, had the new part in 4 days, replaced it in 5 minutes, and the phone is good as new!

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Seth Axen 🪓 @sethaxen.com · Aug 2

I'm from Southern California, I think that was mid-teens for me.

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Seth Axen 🪓 @sethaxen.com · Aug 2

Have you reached waging-war-on-invasive-plant-species age?

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Seth Axen 🪓 @sethaxen.com · Jul 31

Sharing this here a bit late, but @vstaros.bsky.social and I wrote a little something about our experience contributing to the @sbi-devs.bsky.social (simulation-based inference) hackathon. @mlcolab.org @mackelab.bsky.social

We were obviously very hungry while writing.

A retrospective on the 2025 SBI Hackathon

You walk into a bakery, take one bite of a still-warm pastry, and think: “Whoa - there’s rye flour, a hint of orange zest, maybe cardamom… and is that buckwheat honey?” From that single taste you begi...

mlcolab.org

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Seth Axen 🪓 @sethaxen.com · Jul 24

Now back to some particularly thorny math needed just to write an informative docstring message.

Seth Axen 🪓 @sethaxen.com · Jul 24

Spent a pleasant morning organizing GitHub repos and notifications, responding to issues and PRs, and answering questions on Slack. Reminder that FOSS is often about building a community as much as building software!

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Reposted by Seth Axen 🪓

Martin Trapp @trappmartin.bsky.social · Jul 21

Remember that computers use bitstrings to represent numbers? We exploit this in our recent @auai.org paper and introduce #BitVI.

#BitVI directly learns an approximation in the space of bitstring representations, thus, capturing complex distributions under varying numerical precision regimes.

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Seth Axen 🪓 @sethaxen.com · Jul 15

I know what you're thinking: "What a cute little Easter egg!" Except no, if you search for "qr <anything>", you get a QR code for "<anything>".

Seth Axen 🪓 @sethaxen.com · Jul 15

If you run a DuckDuckGo search for "qr decomposition", it returns a QR code for "decomposition".

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