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Show HN: Mermaid Formatter – CLI and library to auto-format Mermaid diagrams

https://github.com/chenyanchen/mermaid-formatter
1•astm•9m ago•0 comments

RFCs vs. READMEs: The Evolution of Protocols

https://h3manth.com/scribe/rfcs-vs-readmes/
1•init0•16m ago•1 comments

Kanchipuram Saris and Thinking Machines

https://altermag.com/articles/kanchipuram-saris-and-thinking-machines
1•trojanalert•16m ago•0 comments

Chinese chemical supplier causes global baby formula recall

https://www.reuters.com/business/healthcare-pharmaceuticals/nestle-widens-french-infant-formula-r...
1•fkdk•19m ago•0 comments

I've used AI to write 100% of my code for a year as an engineer

https://old.reddit.com/r/ClaudeCode/comments/1qxvobt/ive_used_ai_to_write_100_of_my_code_for_1_ye...
1•ukuina•21m ago•1 comments

Looking for 4 Autistic Co-Founders for AI Startup (Equity-Based)

1•au-ai-aisl•31m ago•1 comments

AI-native capabilities, a new API Catalog, and updated plans and pricing

https://blog.postman.com/new-capabilities-march-2026/
1•thunderbong•31m ago•0 comments

What changed in tech from 2010 to 2020?

https://www.tedsanders.com/what-changed-in-tech-from-2010-to-2020/
2•endorphine•36m ago•0 comments

From Human Ergonomics to Agent Ergonomics

https://wesmckinney.com/blog/agent-ergonomics/
1•Anon84•40m ago•0 comments

Advanced Inertial Reference Sphere

https://en.wikipedia.org/wiki/Advanced_Inertial_Reference_Sphere
1•cyanf•42m ago•0 comments

Toyota Developing a Console-Grade, Open-Source Game Engine with Flutter and Dart

https://www.phoronix.com/news/Fluorite-Toyota-Game-Engine
1•computer23•44m ago•0 comments

Typing for Love or Money: The Hidden Labor Behind Modern Literary Masterpieces

https://publicdomainreview.org/essay/typing-for-love-or-money/
1•prismatic•45m ago•0 comments

Show HN: A longitudinal health record built from fragmented medical data

https://myaether.live
1•takmak007•47m ago•0 comments

CoreWeave's $30B Bet on GPU Market Infrastructure

https://davefriedman.substack.com/p/coreweaves-30-billion-bet-on-gpu
1•gmays•59m ago•0 comments

Creating and Hosting a Static Website on Cloudflare for Free

https://benjaminsmallwood.com/blog/creating-and-hosting-a-static-website-on-cloudflare-for-free/
1•bensmallwood•1h ago•1 comments

"The Stanford scam proves America is becoming a nation of grifters"

https://www.thetimes.com/us/news-today/article/students-stanford-grifters-ivy-league-w2g5z768z
3•cwwc•1h ago•0 comments

Elon Musk on Space GPUs, AI, Optimus, and His Manufacturing Method

https://cheekypint.substack.com/p/elon-musk-on-space-gpus-ai-optimus
2•simonebrunozzi•1h ago•0 comments

X (Twitter) is back with a new X API Pay-Per-Use model

https://developer.x.com/
3•eeko_systems•1h ago•0 comments

Zlob.h 100% POSIX and glibc compatible globbing lib that is faste and better

https://github.com/dmtrKovalenko/zlob
3•neogoose•1h ago•1 comments

Show HN: Deterministic signal triangulation using a fixed .72% variance constant

https://github.com/mabrucker85-prog/Project_Lance_Core
2•mav5431•1h ago•1 comments

Scientists Discover Levitating Time Crystals You Can Hold, Defy Newton’s 3rd Law

https://phys.org/news/2026-02-scientists-levitating-crystals.html
3•sizzle•1h ago•0 comments

When Michelangelo Met Titian

https://www.wsj.com/arts-culture/books/michelangelo-titian-review-the-renaissances-odd-couple-e34...
1•keiferski•1h ago•0 comments

Solving NYT Pips with DLX

https://github.com/DonoG/NYTPips4Processing
1•impossiblecode•1h ago•1 comments

Baldur's Gate to be turned into TV series – without the game's developers

https://www.bbc.com/news/articles/c24g457y534o
3•vunderba•1h ago•0 comments

Interview with 'Just use a VPS' bro (OpenClaw version) [video]

https://www.youtube.com/watch?v=40SnEd1RWUU
2•dangtony98•1h ago•0 comments

EchoJEPA: Latent Predictive Foundation Model for Echocardiography

https://github.com/bowang-lab/EchoJEPA
1•euvin•1h ago•0 comments

Disablling Go Telemetry

https://go.dev/doc/telemetry
1•1vuio0pswjnm7•1h ago•0 comments

Effective Nihilism

https://www.effectivenihilism.org/
1•abetusk•1h ago•1 comments

The UK government didn't want you to see this report on ecosystem collapse

https://www.theguardian.com/commentisfree/2026/jan/27/uk-government-report-ecosystem-collapse-foi...
5•pabs3•1h ago•0 comments

No 10 blocks report on impact of rainforest collapse on food prices

https://www.thetimes.com/uk/environment/article/no-10-blocks-report-on-impact-of-rainforest-colla...
3•pabs3•1h ago•0 comments
Open in hackernews

Z3 API in Python: From Sudoku to N-Queens in Under 20 Lines (2015)

https://ericpony.github.io/z3py-tutorial/guide-examples.htm
155•amit-bansil•2mo ago

Comments

skopje•2mo ago
Very good to see all this in one short page!
stevesimmons•2mo ago
It's worth noting these notes are 11 years old. The first give-away was the comment that in Python 3/2 is an integer, which is indeed true in Python 2 but not in Py3.

For modern users of Z3, you'd want to do `pip install z3-solver` rather than use `Z3Py` mentioned at the very bottom of this doc.

almostgotcaught•2mo ago
https://www.hakank.org/z3/
__alexander•2mo ago
Thank you for the link.
brap•2mo ago
That’s a very clean API.
cess11•2mo ago
It's very close to the SMTLIB API.

Page 19 in https://smt.st/SAT_SMT_by_example.pdf shows an example in both Python and SMTLIB. After looking at a guide like TFA this book is a good next step.

tombert•2mo ago
Solvers are something that still kind of feel like magic to me. I have done a fair amount of Isabelle, and the "sledgehammer" tool in there (which uses solvers to see if an existing proof can be made to work to solve your subgoal) is something that impresses me every single time I use it.
nextaccountic•2mo ago
On same level of abstraction I think it's useful to view those tools as some form of constraint solving. Think how you can solve sudoku with pen and paper by writing out each possibility, then fill squares either because it has only one possibility or by making guesses. After you fill a square, you can then update your possible states (propagate constraints), and repeat until you solve it or hit an impossible solve (in which case you need to backtrack on some earlier guess).

The algorithms differ mainly in how they keep track of all possibilities and how they update them

I think this answer is pretty good https://cstheory.stackexchange.com/a/29428 (take note at the end "sat is csp on boolean domains")

tyilo•2mo ago
I have created a Python library called "z4-solver" that adds some nice utility functions on top of z3: https://github.com/Tyilo/z4

I always use that instead of the z3-solver directly.

Recursing•2mo ago
Have you tried to compare Z3 with cvc5? https://cvc5.github.io/docs/cvc5-1.1.2/api/python/pythonic/p...

It offers basically the same API and could be faster in many cases

gignico•2mo ago
I was about to comment the same. Z3 always takes all the credit but cvc5 is just as great!
raphman•2mo ago
"SAT/SMT by Example" also contains many Z3 examples (and has a new URL): https://smt.st/
philzook•2mo ago
I'm a fan. I've been building a proof assistant directly on the z3py api. https://pypi.org/project/knuckledragger/0.1.3/
gbacon•2mo ago
We care about Z3 because it is a Satisfiability Modulo Theories (SMT) solver.

Satisfiability: In 1971, Stephen A. Cook established that Boolean satisfiability, given an arbitrary Boolean formula whether an assignment to its variables exists that evaluates true, is NP-complete.

https://dl.acm.org/doi/10.1145/800157.805047

Translating between NP-complete problems is at most a polynomial (“fast”) amount of work, so every improvement gained on satisfiability (whose worst case is exponential rather than polynomial time complexity) benefits all other NP-complete problems, and thus the rest of NP.

Modulo Theories: We can think of SMT as a high-level language that automates encoding of other problems into raw Boolean formulas. Applications built on Z3 outsource search by encoding problems via one or more theories and then decoding results back to the problem domain at hand.

The benefits of doing this are (1) using an existing robust, well-tested suite of algorithms where (2) lots of research effort is concentrated and (3) improvements to Z3 improve your problem’s results more-or-less for free. According to Microsoft, “Z3 is used in a wide range of software engineering applications, ranging from program verification, compiler validation, testing, fuzzing using dynamic symbolic execution, model-based software development, network verification, and optimization.”

https://www.microsoft.com/en-us/research/project/z3-3/

See also:

https://github.com/Z3Prover/z3