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Rado Kirov

@radokirov

engineering at stripe. recovering academic.

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06.07.2023
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Latest posts by Rado Kirov @radokirov

I asked Claude code to formalize with lean a proof for the knuth 3d hamiltonian cycles problem (odd cases for now) that also solved experimentally by claude - www-cs-faculty.stanford.edu/~knuth/paper...

github.com/rkirov/claud...

Read more in the human notes section in the README.

07.03.2026 04:10 πŸ‘ 1 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

If they teach it directly with AI, they are not matching their own journey and might fail to translate the right lessons.

There is also a timing risk. The ai of tomorrow might not need steering. By the time you finish the course it might not be as needed.

07.03.2026 03:45 πŸ‘ 3 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

Big +1, steering is mandatory today and it does involve at minimum reading the code. The main problem as I see it is everyone adept at steering has learned that pre-AI mostly by writing a lot of code. But if they teach newcomers to practice without AI the same would be seen as luddites.

07.03.2026 03:45 πŸ‘ 4 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

Waiting til your 40s when you get all the benefits of the 30s plus a much more visceral feeling (e.g. back pain) that you don’t have much time left and you better be efficient about it :)

27.02.2026 21:37 πŸ‘ 5 πŸ” 1 πŸ’¬ 0 πŸ“Œ 0

Yes probably something like tikz.dev is best.

17.02.2026 02:08 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

On the flip side crafting the diagram is laborious (moving the boxes, drawing the arrows) and as such should be prime for AI boost. Isn’t there a split the difference approach where the human does the knowledge distillation into some textual description but AI generates the final diagram?

16.02.2026 22:52 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
From Sets in Math to Types in Lean: Subtype, Fin, Set, Finset, and Fintype Preface: Why All Mathematicians Should Learn Lean LLMs can generate plausible-sounding proofs at unprecedented speed and scale. Some are correct, many are not, and LLMs themselves cannot reliably tell...

New blog post - From sets in math to types in Lean rkirov.github.io/posts/sets-v...

16.02.2026 00:37 πŸ‘ 3 πŸ” 1 πŸ’¬ 0 πŸ“Œ 0
Leaning on AI Leaning on AI It’s been five months since my last dedicated Lean post and as usual I have started to lose steam on Lean projects. After the thrill of discovering the world of formalized mathematics st...

Leaning on AI - new blog post about using AI to learn Lean rkirov.github.io/posts/lean5/

09.02.2026 06:38 πŸ‘ 5 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0
Is this JS function pure? Is this JS function pure? In 2019, as functional programming was making the last inroads dethroning OOP, I kept hearing the mantra of β€œjust use pure functions” in JS. Something didn’t sit right with m...

"Is this JS function pure?" - wrote a short blog post summary of the pure JS function poll I ran in 2019
rkirov.github.io/posts/pure/

12.11.2025 06:38 πŸ‘ 4 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0
Alligator Eggs!

All of this should be equivalent to visualizing lambda calculus (by Curry-Howard), which opens to more visualizations/gamifications.

But which one would make the best mobile puzzle game?

[1] worrydream.com/AlligatorEggs/
[2] bntr.itch.io/visual-lambda
[3] github.com/prathyvsh/la...

08.11.2025 22:12 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0
The Incredible Proof Machine

Falling in an odd rabbit-hole of visualizing logical deductions.

Why isn't there a mobile friendly game for proving the ~100 core theorems of propositional and first-order logic?

[1] incredible.pm
[2] www.winterdrache.de/freeware/dom...
[3] www.jfsowa.com/peirce/ms514...

08.11.2025 22:07 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

AI boosts productivity until a breaking point where domain expertise becomes unnecessary (coding, formalizing math, etc.) - you can go straight from idea to implementation without interaction with the underlying tool. Some are betting that arrives soon enough that they don’t invest in learning.

02.11.2025 01:12 πŸ‘ 2 πŸ” 0 πŸ’¬ 2 πŸ“Œ 0
Post image

You can’t convince me Russell wouldn’t have used Lean if he had a chance.

27.10.2025 05:28 πŸ‘ 5 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0
Why formalize mathematics - more than catching errors Why formalize mathematics - more than catching errors I read a good post by one of the authors of the Isabelle theorem prover, that got me thinking. The author, Lawrence Paulson, observed that most ma...

new blog post - Why formalize mathematics - more than catching errors rkirov.github.io/posts/why_le...

18.10.2025 07:34 πŸ‘ 3 πŸ” 2 πŸ’¬ 0 πŸ“Œ 0

Can wait to see a Fields medalist asking what’s the difference between common js and EcmaScript modules.

13.10.2025 23:00 πŸ‘ 6 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

We got enough interest and are kicking this off this Monday 7:00pm at moxsf.com. Fill in the interest form if you would like to join us.

11.10.2025 21:42 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

We got 11 sign-up so this might happen. One sign-up mistyped their email, and I couldn't reach them, so if you didn't get an email from me, please redo the form.

Next up, finding a venue.

28.09.2025 00:36 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

I will consider it if I start to feel I need something that it can provide on top of my low tech tools, but also don’t want to involve more parties in this too prematurely.

24.09.2025 17:38 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

Haven’t done this before, so I might be forgetting something, but only thing that comes to mind is needs a projector or a big screen.

24.09.2025 17:36 πŸ‘ 1 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0
Preview
Mathematics from Scratch in Lean Mathematics from Scratch with Lean In the 1890s, the world's top mathematicians embarked on an ambitious project: rebuild all of mathematics from scratch using pure logic. Today, you can join that sam...

course info - docs.google.com/document/d/1...

interest collection form - docs.google.com/forms/d/e/1F...

24.09.2025 05:05 πŸ‘ 8 πŸ” 1 πŸ’¬ 1 πŸ“Œ 0

Calling Bay Area math enthusiasts interested in weekly sessions doing rigorous foundational mathematics the modern way - with computer-verified proofs in Lean.

(An experiment in rigorous math education outside traditional academia)

24.09.2025 05:05 πŸ‘ 40 πŸ” 8 πŸ’¬ 5 πŸ“Œ 2

Er reals

22.09.2025 15:17 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

Bad news - you have two more instances of this ahead, trichotomy of rationals and integers.

22.09.2025 15:16 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

Yeah from my very limitted experience, they don’t really show up much when doing standard mathematics. Mostly lean getting stuck in dealing with universe polymorphism and one has to explicitly add universe parameters.

22.09.2025 15:15 πŸ‘ 2 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

Do you plan to go into universes for the type system post?

22.09.2025 15:06 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

But also where a new lean users needs most help due to the proliferation of tactics, with different powers and tradeoffs. So the first post would cover a lot of ground (also very dependent on the type of math one is trying to prove) but be more valuable long term.

22.09.2025 14:40 πŸ‘ 3 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

One needs to understand the type system in order to prove anything so the second feels like a prerequisite for the first. Also from what I gather Lean types, while crazy fancy for people new to proof assistants, are a fairly standard construction. The extensibility model is where Lean shines.

22.09.2025 14:40 πŸ‘ 2 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
Learning Lean: Part 4 It’s been 3 months since my previous post about learning Lean part 3, so it’s time to write another one. I have mostly continued to work through Tao’s Analysis book through his excellent companion - w...

Newest installment in my journey of learning how to do math proofs with computers rkirov.github.io/posts/lean4/.

22.09.2025 06:22 πŸ‘ 13 πŸ” 2 πŸ’¬ 0 πŸ“Œ 0

On the (I hate Fins) part - I wonder if this proof in a set theory based assistant would look simper. Part of the problem is - Fins are whole types e.g. 3 in Fin 4 is very different from 3 in Fin 5. Tao suggested avoiding Fins by redefining Permutations as N -> N bijections that are id after n.

18.09.2025 03:56 πŸ‘ 1 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

3) I am convinced this will be the only way to do math in 10-20 years, so fun to be part of the revolution as it is unfolding and maybe bring some experience from the software engineering world. These exercises are just a formal math proof version of the CS exercises we all did to learn programming.

18.09.2025 03:51 πŸ‘ 1 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0