apalache

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<img
src="https://raw.githubusercontent.com/informalsystems/apalache/99e58d6f5eebcc41f432a126a13a5f8d2ae7afe6/logo-apalache.svg"
alt="Apalache Logo">

<h1><a href="https://apalache-mc.org/">APALACHE</a></h1>

<p>A symbolic model checker for TLA+<p>

</div>

[![build](https://github.com/apalache-mc/apalache/actions/workflows/main.yml/badge.svg)](https://github.com/apalache-mc/apalache/actions/workflows/main.yml)

Apalache translates [TLA+][] into the logic supported by SMT solvers such as
[Microsoft Z3][] and [CVC5][]. Apalache can check inductive invariants (for fixed or bounded
parameters) and check safety of bounded executions (bounded model checking). To
see the list of supported TLA+ constructs, check the [supported features][]. In
general, Apalache runs under the same assumptions as [TLC][]. However, Apalache
benefits from constraint solving and can handle potentially larger state-spaces,
e.g., involving integer clocks and Byzantine faults.

To learn more about TLA+, visit [Leslie Lamport's page on TLA+][] and his [Video
course][].

## Releases

Check the [releases page][] for our latest release.

For a stable release, we recommend that you pull the latest docker image with
`docker pull ghcr.io/apalache-mc/apalache:main`, use the jar from the
most recent release, or checkout the source code from the most recent release
tag.

To try the latest cool features, check out the head of the [main branch][].

You can also find Apalache packaged via Nix at [cosmos.nix](https://github.com/informalsystems/cosmos.nix)

For more information on installation options, see [the
manual][user-manual-installation].

## Success stories

Check [Apalache examples][] that demonstrate how to use the strengths of Apalache.
Also, check the [standard repository of TLA+ examples][].

## Getting started

- Read the [Beginner's tutorial][].
- Read the [Apalache user manual][user-manual].
- Consult the (WIP) [Idioms for writing better TLA+][idioms].
- Consult the (WIP) [TLA+ language manual for engineers][language-manual].

## Community

- Discuss the use of Apalache and R&D on the [Apalache Forum][].
- [Contribute](./CONTRIBUTING.md) to the development of Apalache.

## Funding and Sponsorship

Apalache has moved to [TLA<sup>+</sup> Foundation][tlaplus-foundation], under
the [Linux Foundation][linuxfoundation].

We are grateful for the past financial support in the form of grants or
employment from the following organizations:

 - [Informal Systems][] (Canada/Switzerland/Austria): 2020-2024
 - [Vienna Business Agency][] (Austria): 2021-2023
 - [Interchain Foundation][] (Switzerland): 2019-2023
 - [WWTF][] (Austria): Vienna Science and Technology Fund 2016-2020
 - [Inria Nancy][] and [LORIA][] (France): 2018-2019
 - [TU Wien][] (Austria): 2016-2020

More details on the [Funding page](./FUNDING.md).

## Website

Our current website is served at https://apalache-mc.org .

The site is hosted by github, and changes can be made through PRs into the
[gh-pages]