tlaplus
z3
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tlaplus | z3 | |
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38 | 28 | |
2,201 | 9,708 | |
1.2% | 1.7% | |
9.1 | 9.8 | |
8 days ago | 6 days ago | |
Java | C++ | |
MIT License | GNU General Public License v3.0 or later |
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For example, an activity of 9.0 indicates that a project is amongst the top 10% of the most actively developed projects that we are tracking.
tlaplus
- Ask HN: Usefulness of formal verification (Coq) and formal verification (TLA+)?
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Quint: A specification language based on the temporal logic of actions (TLA)
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https://github.com/tlaplus/tlaplus/blob/master/tlatools/org....
In any case, our whole team thinks TLA is great, and we're happy people like you and Ron find it so useful and insightful. We also think it is a very insightful.
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Concurrent Data-structure Design Walk-Through
There are no tests! There are various ways to test concurrent data structures. You could use a stress test, where you spawn a lot of threads and let them mutate the map in a random way and then check the consistency of the map and some invariants. You could learn TLA+ and write a formal model of the map and then verify it.
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In Which I Claim Rich Hickey Is Wrong
Dafny and Whiley are two examples with explicit verification support. Idris and other dependently typed languages should all be rich enough to express the required predicate but might not necessarily be able to accept a reasonable implementation as proof. Isabelle, Lean, Coq, and other theorem provers definitely can express the capability but aren't going to churn out much in the way of executable programs; they're more useful to guide an implementation in a more practical functional language but then the proof is separated from the implementation, and you could also use tools like TLA+.
https://dafny.org/
https://whiley.org/
https://www.idris-lang.org/
https://isabelle.in.tum.de/
https://leanprover.github.io/
https://coq.inria.fr/
http://lamport.azurewebsites.net/tla/tla.html
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Programming Languages Going Above and Beyond
I wish something like Lamport's TLA+ (https://lamport.azurewebsites.net/tla/tla.html) was supported in modern language compilers - perhaps with annotations/macros and a mini formal DSL.
- Ask HN: How you understand TLA+ and how you use TLA+ in your projects?
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A collection of lock-free data structures written in standard C++11
Checking the invariant with assert is also useful in my limited experience with concurrency.
https://lamport.azurewebsites.net/tla/tla.html
- Ask HN: Is writing a math proof like programming without ever running your code?
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What I've Learned About Formal Methods in Half a Year
One advantage of formal methods is in determining "what was expected" (including all the goofy edge cases) without having to burrow into the details of code.
Take a look at Alloy (http://alloytools.org/) and TLA+ (https://lamport.azurewebsites.net/tla/tla.html) for example. (Or even the ancient Z ("Zed") notation (https://www.cs.cmu.edu/~15819/zedbook.pdf)).
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How do I get the set of process identifier of PlusCal?
The pcal generator does *not* generate a definition for the set of labels. However, some users have suggested to add such a feature: https://github.com/tlaplus/tlaplus/issues/613
z3
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Ask HN: What is the current state of "logical" AI?
See https://cacm.acm.org/magazines/2023/6/273222-the-silent-revo... and also modern production rules engines like https://drools.org/
Oddly, back when “expert system shells” were cool people thought 10,000 rules were difficult to handle, now 1,000,000 might not be a problem at all. Back then the RETE algorithm was still under development and people were using linear search and not hash tables to do their lookups.
Also https://github.com/Z3Prover/z3
Note “the semantic web” is both an advance and a retreat in that OWL is a subset of first order logic which is really decidable and sorta kinda fast. It can do a lot but people aren’t really happy with what it can do.
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Lean4 helped Terence Tao discover a small bug in his recent paper
Code correctness is a lost art. I requirement to think in abstractions is what scares a lot of devs to avoid it. The higher abstraction language (formal specs) focus on a dedicated language to describe code, whereas lower abstractions (code contracts) basically replace validation logic with a better model.
C# once had Code Contracts[1]; a simple yet powerful way to make formal specifications. The contracts was checked at compile time using the Z3 SMT solver[2]. It was unfortunately deprecated after a few years[3] and once removed from the .NET Runtime it was declared dead.
The closest thing C# now have is probably Dafny[4] while the C# dev guys still try to figure out how to implement it directly in the language[5].
[1] https://www.microsoft.com/en-us/research/project/code-contra...
[2] https://github.com/Z3Prover/z3
[3] https://github.com/microsoft/CodeContracts
[4] https://github.com/dafny-lang/dafny
[5] https://github.com/dotnet/csharplang/issues/105
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Programming Languages Going Above and Beyond
I believe, Nim also has this functionality, although, it uses the [0]Z3Prover tool with a nim frontend [1]"DrNim" for proving.
[0]https://github.com/Z3Prover/z3
- Modern SAT solvers: fast, neat and underused (2018)
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If You've Got Enough Money, It's All 'Lawful'
Don't get me wrong, there are times when Microsoft got it right the first time that was technically far superior to their competitors. Windows IOCP was theoretically capable of doing C10K as far back in 1994-95 when there wasn't any hardware support yet and UNIX world was bickering over how to do asynchronous I/O. Years later POSIX came up with select which was a shoddy little shit in comparison. Linux caved in finally only as recently as 2019 and implemented io_uring. Microsoft research has contributed some very interesting things to computer science like Z3 SAT solver and in collaboration with INRIA made languages like F* and Low* for formal specification and verification. But all this dwarfs in comparison to all the harm they did.
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Constraint Programming 'linking' variables
Z3 theorem prover SMT solver might help you.
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General mathematical expression analysis system
Other than that, you should look at Z3 which is pretty damn good at these sort of theorems/constraints.
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-🎄- 2022 Day 21 Solutions -🎄-
In the end I used Z3 Julia bindings instead. The hardest part was to get the result back from it, because I kept running into assertion violations from inside Z3
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Question about Predicate Transformer Semantics
I'm trying to learn a little bit about Predicate Transformer Semantics (PTS) as part of a quick exploration of Z3.
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The Little Prover
> And you propose me instead to go and reverse engineer library Js code which I am not that proficient in, and rewrite all code in Java instead?..
Yes, rather than demand others cater to your whims, frankly.
Do you realise how hypocritical it sounds to complain that you are not proficient in Javascript, when others might not be proficient in ?
Go use Z3 if you need a prover in C++ (or Java), its far more robust (provided its the type you're after) than someones 700 LoC JavaScript implementation.
https://github.com/Z3Prover/z3
What are some alternatives?
dafny - Dafny is a verification-aware programming language
employee-scheduling-ui - An UI component for Employee Scheduling application.
coq - Coq is a formal proof management system. It provides a formal language to write mathematical definitions, executable algorithms and theorems together with an environment for semi-interactive development of machine-checked proofs.
advent-of-code - My solutions to http://adventofcode.com/ :)
apalache - APALACHE: symbolic model checker for TLA+ and Quint
advent-of-code-go - All 8 years of adventofcode.com solutions in Go/Golang; 2015 2016 2017 2018 2019 2020 2021 2022
stateright - A model checker for implementing distributed systems.
magmide - A dependently-typed proof language intended to make provably correct bare metal code possible for working software engineers.
awesome-programming-languages - The list of an awesome programming languages that you might be interested in
ikos - Static analyzer for C/C++ based on the theory of Abstract Interpretation.
adventofcode - Advent of Code solutions of 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022 and 2023 in Scala
androguard - Reverse engineering and pentesting for Android applications