Terms of use

Last updated 23 September 2026

The service

clopen.solutions is a free registry of open mathematical problems and of papers that claim to resolve them, run by Clemens Thalhammer, Switzerland (contact@clopen.solutions). By using it you accept these terms. The service may change or stop at any time.

Accounts

Each account needs a curator's approval. Give accurate details, and don't let anyone else use your account. You can delete it at any time from your profile page. An account that breaks these terms may be suspended or closed.

Submitting a paper

By submitting, you confirm that you have the right to do so, that every co-author agrees to the submission, its automated review and its publication here, and that it infringes nobody's rights.

You keep your copyright. You grant the operator a non-exclusive, worldwide, free and permanent licence to store, build, review, publish and distribute the paper, its sources, any Lean code and its details, including through the providers named in the privacy policy. The licence you choose for the paper and code governs what others may do with them.

An announced version is permanent. It can be withdrawn, but not edited or deleted; corrections are new versions.

Automated review and badges

Before a submission can be announced, an AI model reviews it, as the privacy policy describes. It can stop an announcement only if the submission isn't a paper, is empty or malformed, is off-topic, or doesn't address the problem it claims. You can ask a curator to review that at contact@clopen.solutions.

A problem's status and a paper's badges report the evidence on record. They are not an endorsement, and nobody guarantees that a paper is correct.

What is not allowed

• Content that is unlawful, or that you have no right to share.
• Naming someone as an author without their consent.
• Trying to manipulate the automated review, for example with hidden instructions to the model.
• Attacking the site, or using its build sandboxes for anything but building your submission.

Moderation

Curators and admins review content by hand, helped by the automated review and a scan for hidden instructions. Where content breaks these terms or the law, an admin may attach a public notice to it, withhold or revoke a badge, remove it, or suspend the account. The author is told why, and can ask for the decision to be reviewed by writing to contact@clopen.solutions.

Reporting content

To report content you believe is illegal, write to contact@clopen.solutions with the page's address, what is wrong and why. You will be told what was decided. The same address is the point of contact for users and authorities, in English or German.

Liability

The service is provided as it is, without warranty. The operator is liable only for intent and gross negligence, as far as the law allows.

Changes and law

When these terms change, the date at the top changes, and account holders are emailed about any material change. If you don't accept a change, you can delete your account. Swiss law applies, without prejudice to any mandatory consumer protection of the country you live in.