v0.2

New geometric kernel that just works, kernels.MaternGeometricKernel. Relies on (hopefully) sensible defaults we defined. Mostly by @stoprightthere.

New spaces, based on Azangulov et al. (2022, 2023), mostly by @imbirik and @stoprightthere:

• hyperbolic spaces $\mathbb{H}_n$ in spaces.Hyperbolic,
• manifolds of symmetric positive definite matrices $\mathrm{SPD}(n)$ endowed with the affine-invariant Riemannian metric in spaces.SymmetricPositiveDefiniteMatrices,
• special orthogonal groups $\mathrm{SO}(n)$ in spaces.SpecialOrthogonal.
• special unitary groups $\mathrm{SU}(n)$ in spaces.SpecialUnitary.

New package geometric_kernels.feature_maps for (approximate) finite-dimensional feature maps. Mostly by @stoprightthere.

New small package geometric_kernels.sampling for efficient sampling from geometric Gaussian process priors. Based on the (approximate) finite-dimensional feature maps. Mostly by @stoprightthere.

Examples/Tutorials improvements, mostly by @vabor112:

• new Jupyter notebooks Graph.ipynb, Hyperbolic.ipynb, Hypersphere.ipynb, Mesh.ipynb, SPD.ipynb, SpecialOrthogonal.ipynb, SpecialUnitary.ipynb, Torus.ipynb featuring tutorials on all the spaces in the library,
• new Jupyter notebooks backends/JAX_Graph.ipynb, backends/PyTorch_Graph.ipynb, backends/TensorFlow_Graph.ipynb showcasing how to use all the backends supported by the library,
• new Jupyter notebooks frontends/GPflow.ipynb, frontends/GPJax.ipynb, frontends/GPyTorch.ipynb showcasing how to use all the frontends supported by the library,
• other notebooks updated and grouped together in other/ folder.

Documentation improvements, mostly by @vabor112:

• all docstrings throughout the library revised,
• added new documentation pages describing the basic theoretical concepts, in docs/theory,
• notebooks are now rendered as part of the documentation, you can refer to them from the docstrings and other documentation pages,
• introduced a more or less unified style for docstrings.

Other:

• refactoring and bug fixes,
• added type hints throughout the library and enabled mypy,
• updated frontends (with limited suppot for GPJax due to conflicting dependencies),
• improved spaces.ProductDiscreteSpectrumSpace and kernels.ProductGeometricKernel,
• filtered out or fixed some annoying external warnings,
• added a new banner for README.md and for our landing page, courtesy of @aterenin,
• example notebooks are now run as tests,
• we now support Python 3.8, 3.9, 3.10, 3.11 and have test workflows for all the supported Python versions,
• we now provide a PyPI package,
• LAB is now a lightweight dependency, thanks to @wesselb,
• kernels are now normalized to have unit outputscale by default.