# Licensing

Topological Fixed Point Theory uses two licenses for different kinds of material. This is a code and content split; it is not a choice between two licenses for the entire repository.

| Material owned by the TFPT contributors | License |
|---|---|
| Software, including Python, Lean, Wolfram, shell scripts, website implementation, build tools, configuration and reusable typesetting tools | [Apache License 2.0](LICENSE), SPDX identifier `Apache-2.0` |
| Scientific papers, their authored LaTeX text, explanatory documentation, original scientific figures and diagrams, and the corresponding published PDFs | [Creative Commons Attribution 4.0 International](LICENSE-CONTENT), SPDX identifier `CC-BY-4.0` |

The software allocation includes project owned code in `verification/`, `scripts/`, `experiments/`, `tfpt_explorer/` and `website/`, and the Lean and Wolfram developments. The content allocation includes project owned scientific material in `documents/`, root paper entry points, `docs/`, `articles/`, `universal_room/`, scientific figure sources and the published paper downloads. File location does not override a specific existing third party notice.

The website's implementation is Apache 2.0. Its original explanatory text and scientific illustrations are CC BY 4.0. Reusable typesetting code such as `tex-artefacts/tfpt_style.tex` is software; the scientific text and figure content it formats remain content. Code examples intended to run as software follow the software license even when shown inside documentation.

## Generated material and scientific facts

Copies and generated presentations of covered material follow the allocation of their source. A generated source browser does not change the license of the code or text it displays. Existing third party excerpts retain their original terms.

This declaration grants only rights held by the TFPT contributors. It does not claim copyright over mathematical facts, physical laws or numerical values. Scientific citation and the precise scope of a result remain separate from permission to reuse its presentation.

## Third party material

Third party dependencies, fonts, images, quotations and other incorporated works are excluded from the project's default grants. Keep their existing copyright and license notices. In particular:

- Inter: [SIL Open Font License 1.1](website/public/fonts/OFL-inter.txt).
- JetBrains Mono: [SIL Open Font License 1.1](website/public/fonts/OFL-jetbrainsmono.txt).
- Newsreader: [SIL Open Font License 1.1](website/public/fonts/OFL-newsreader.txt).
- Bundled KaTeX font distribution: [its existing MIT notice](website/public/fonts/katex/LICENSE.txt).
- Dependencies installed by Python, npm or Lean retain their upstream licenses.

Separately identified projects keep their own licensing and publication scope. The archived Prime Front explainer material in `videos/prime-front-explainer-2026-08/` is outside the TFPT default grants.

A file with a specific third party license or attribution keeps that notice. The absence of a notice does not establish that incorporated material belongs to the TFPT contributors.

## Attribution and publication versions

Preserve the notices required by the applicable license, identify modifications as required, and cite the scientific paper edition used. The publication authors are Stefan Hamann and Alessandro Rizzo; individual software contributions retain their respective authorship. The [NOTICE](NOTICE) file accompanies the software grant.

This policy records the current licensing declaration. The current project owned experiment package metadata follows Apache 2.0; previously granted MIT permissions for older versions remain valid. Historical publication dates, immutable archives and previously granted licenses are not rewritten. Consult the notices accompanying the edition or third party work being reused.

The complete license texts control the permissions and conditions. For questions about the scope of a particular file, use the [repository issues](https://github.com/sthamann/topological-fixed-point-theory/issues).