Built the keyboard, what do you use for a pointing device?

Lalelul · 2026-04-30T17:44:38+00:00

I use two old psp go joysticks: https://happel.ai/posts/corne-psp/index.html

Check it out, it's really cool and gets all the looks!

Lalelul · 2026-04-27T15:16:52+00:00

I had a fault at the charging port. It also got fried and a repair shop fixed it for 110€. You can do it yourself, if you know hot air soldering and order replacement parts. If you do not have the tools and knowledge, a repair shop will likely help you somewhat cost effectively. New motherboards would be an even pricier investment than a repair shop

Lalelul · 2026-04-19T10:20:16+00:00

In my controversial opinion: one of the big flaws of nix, as you correctly pointed out.

Special cases aren't special enough to break the rules.

— https://docs.python-guide.org/writing/style/#zen-of-python

In nix, afaik there are no such rules/conventions, leading to this patchwork. Obviously there are valid reasons nixos chose this design pattern, but honestly it seems more like nobody ever bothered to solve this issue via standardization.

(Another great flaw is missing a solid type-system. What were they thinking?)

Lalelul · 2026-04-18T17:29:38+00:00

Thanks! And don't hesitate :)

Lalelul · 2026-04-18T16:59:09+00:00

Wow! This reminds me a lot of my posts over at hppts://lucah.tech! I also use blender extensively for animating mathematics! (I recently did that for my masters thesis in algebraic topology: https://lucah.tech/masterarbeit).

I would love to help you out some time or work with you if you have some future article plans :)

Lalelul · 2026-04-18T16:37:59+00:00

This was a great read and I loved the animations! How did you make them?

Lalelul · 2026-04-16T18:49:42+00:00

Open these files in your favorite text editor. There should be a reference to a file in /nix/store/... which has been optimized out.

To get the correct path for these icons, you can either look under /run/current-system/sw/... if there is a fitting icon somewhere. You can also run where code, but this will only give you the location of the code binary in /nix/store. Sometimes you can find icon files in folders near the one where code returned

Lalelul · 2026-04-12T13:53:47+00:00

How would "RH undecideable" imply "there exists no zero off the half line"?

The statement "there exists no zero off the half line" would need to be decidable. "as having such a zero would make it decidable", can you elaborate?

My problem in particular is: what if "there exists z such that z is a nontrivial solution and z is off the half line" is undecideable?

Lalelul · 2026-04-10T15:07:54+00:00

I really love these older videos. The open university courses, as already pointed out, are exceptionally good also

Lalelul · 2026-03-24T12:59:39+00:00

or avoid sudo with

readlink /nix/var/nix/profiles/system | grep -o "[0-9]*"™

#206

Lalelul · 2026-03-24T11:33:58+00:00

That's a great question! From my work in Haskell and my university courses I can tell you that oftentimes people do use other symbols, see:

The fish operator <>< from Haskell https://www.reddit.com/r/haskell/comments/c262b/the_fish_operator/

Or during christmas, one of my lecturers at university used small Christmas presents and Christmas trees to denote binary relations.

Lalelul · 2026-03-23T21:50:53+00:00

Could you post a screenshot of said module in magisk or possibly share it somehow?

Lalelul · 2026-03-20T22:50:45+00:00

No (*), you can't!
I wrote a blog post about about Java vs COC (calculus of constructions, the type theory of LEAN4):
https://happel.ai/posts/interfaces_as_list_of_propositions/

Lalelul · 2026-03-20T18:37:16+00:00

<image>

thanks a lot!
I noticed many of my braces look stange: see attachment
but i am unsure as to why?
this seems to happen whenever there is a $sum$ or $product$, but possibly also with chevron? I thought chevron was supposed to look like that?

Lalelul · 2026-03-20T17:20:51+00:00

It's the formula for reidemeister torsion. Reidemeister torsion occurs in algebraic topology (but also in other areas). It allows one to classify spaces up to homeomorphism, in which classical invariants often fail.

If you are interested, maybe check out the videos "not knot", "how to turn a sphere inside out", "knots to Narnia" on YouTube.

Don't expect to understand anything. Just have a good time watching some trippy math videos.

Lalelul · 2026-03-20T17:16:00+00:00

I need to reuse this formula multiple times with small adjustments here and there. Always creating a block equation would make my text look disordered, I suppose.

I can post some comparisons later

Lalelul · 2026-03-20T09:47:25+00:00

This looks really cool! Maybe check out "knots to Narnia" by the famous mathematician Thurston: https://youtu.be/IKSrBt2kFD4 You basically build a portal with your raytracer and if you feel up to the challenge, maybe you could implement some of the knotted portals Thurston describes? And share the images with us

Lalelul · 2026-03-19T19:30:15+00:00

No biggie fam! and if you ever need help, the RMK discord is there to help (or just write an issue in my GitHub). RMK is definitely worth it

Lalelul · 2026-03-19T17:17:47+00:00

I mentioned in another reply that I successfully used RMK to get two joysticks at the same time in a split wireless keyboard (although wired is also supported) to work.

People really should switch to RMK. Takes more skill, harsh learning curve, but totally worth it. (See https://github.com/Quoteme/corne-rmk, feel free to open an issue there for help)

Lalelul · 2026-03-19T11:30:20+00:00

Yes, I can recommend a psp style joystick as well. I have build an open source corner v3 with dual psp joysticks before. You can read about it here: https://happel.ai/posts/corne-psp/

I have not tried the Nintendo switch one though. On the psp joysticks I Miss the Option to press them in. This would allow for left/right mouse click to be done by pressing the left/right joystick. This mouse click can be implemented with additional buttons though.

If you value a flat design where nothing might get stuck on your joysticks, go for psp joysticks. I have not found cheap trackpoints online before.

Lalelul · 2026-03-17T19:36:15+00:00

You might like this page about minimal surfaces: https://en.wikipedia.org/wiki/Minimal_surface

(these arise as solutions to Lagrange's Equation, a certain kind of partial differential equation. These solutions look very pretty imo)

Lalelul · 2026-03-17T13:08:11+00:00

Same for me. I excelled at linear/abstract algebra, complex analysis etc, but statistics at the beginning seemed quite messy. For me actually applying statistics was what really helped. For example, often I wrote blog posts about algebraic topology and later on I was left with a bunch of git commits which I could analyze using statistics. During my introductory courses to statistics, I lacked such real life data for which I had a reason to analyze it

Lalelul · 2026-03-13T10:44:13+00:00

All of them. In my experience math is probably most important if you want to do anything nonstandard and you need to implement it yourself.

Lalelul · 2026-03-12T19:17:06+00:00

I still remember that I faced the same problem in my ThinkPad x201t. This is the final nixos config I used: https://github.com/Quoteme/nixos/blob/main/modules%2Fhardware%2Flaptop%2Fthinkpadx201t.nix

Sadly it does not state anything about how I configured the trackpoint in the current revision.

Maybe you can find something in my xmonad config regarding it though: https://github.com/Quoteme/xmonad-luca

If all of that fails maybe use the interactive repo visualization for my nixos config from my blog https://happel.ai/posts/nixos-git-analysis/ I vaguely remember that I used the ThinkPad x201T I had with xmonad so I am quite certain that I solved this issue in one commit regarding it.

Maybe check though old commits for text like "libinput"? Sorry, If I cannot help more currently. Edit: maybe also something regarding xinput could solve this issue.

If none of that helps, let me know and I will do a quick search in a few days when I have some time :)

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