= Requirements =

We use the following rules to decide which versions of operating systems, compilers, Python and other tools we test:

 * Python: we test the default Python version of the two latest Ubuntu LTS releases.
 * GCC and Clang on Ubuntu: the latest GCC and Clang versions available via apt on the latest two Ubuntu LTS releases and the default GCC version in the latest Ubuntu LTS release.
 * Clang on macOS: we test the default !AppleClang compiler on the latest two macOS versions available on !GitHub actions.
 * MSVC on Windows: we test the default MSVC compiler that comes with the Visual Studio version on the latest two Windows versions available on !GitHub actions.
 * LP solvers (CPLEX and !SoPlex): we test one specific version. We only upgrade the tested version if the current version no longer works or someone wants to test a newer version instead.
 * CMake: we test the default CMake version that comes with the operating systems we test on !GitHub Actions.

See the `README.md` file in the repository for what this means in terms of concrete version numbers.