Terms of Service

Last updated October 13, 2026

Lemmas is a training workspace for competition mathematics. Using it means agreeing to what follows.

Your account

You are responsible for keeping your password and recovery codes private. Recovery codes are shown once at signup and are the only way back into an account with a forgotten password; if you lose both the password and every code, the account and its history cannot be recovered by anyone, including the operator.

One account is for one person. Do not share credentials or attempt to access another learner’s account or data.

Acceptable use

• Do not attempt to extract the full problem bank, solutions, or answer keys through automated requests.
• Do not use Lemmas during a live competition, or in any way that violates the rules of a contest you are entered in.
• Do not probe, scan, or attempt to defeat the authentication, rate limiting, or account isolation.
• Do not upload content into scratchpads that is unlawful, or that infringes someone else’s rights.
• Do not use usernames, friend requests or the notes you send to harass, impersonate or pressure anyone, or to share personal information. Block anyone who bothers you; accounts that abuse these features may be removed.

What you write

Solutions you post under a problem and posts on the Feedback board are yours. By posting you let Lemmas show them, with your username, to other signed-in learners, and keep them until you remove them or delete your account. Write in your own words: do not paste a published solution, and do not post anything abusive, anything personal about someone else, or any link or contact detail. Lemmas may hide or remove what is reported or breaks these terms.

Problem content and rights

The problem bank mixes material under different terms, and the distinction matters:

• Lemmas originals are authored for this project and are labeled as such.
• MAA / AMC problems are reproduced with permission from the Mathematical Association of America and remain their copyrighted material.
• Stanford Math Tournament problems are reproduced under their published release terms with the required citation.
• ARML problems are used for noncommercial education with the project’s approval, as ARML’s booklets allow, and each links back to ARML.
• HMMT and HMIC problems are used with HMMT’s written permission.
• PUMaC problems are used with PUMaC’s written permission.

Your permission to use this material is limited to your own study inside Lemmas. These terms do not let you republish or redistribute it, or build a competing product from it, and for third-party material the operator has no right to grant that. Every record carries its rightsholder and attribution, which must be preserved wherever a problem is quoted.

Your own work

Your scratchpads, notes, and practice history remain yours. The operator stores them only to run the service, does not claim ownership of them, and does not use them to train models. You can export them or delete them from Settings at any time.

Availability and accuracy

Lemmas is provided as is, without warranty. Problem statements, answers, and solution sketches are prepared carefully but may contain errors; they are study material, not an authoritative record of any competition. Always check an official source when accuracy matters. The service may be unavailable, and features may change or be removed.

Ending access

You may delete your account at any time from Settings. The operator may suspend or remove an account that breaks these terms, particularly for bulk extraction of problem content or attempts to reach another learner’s data.

Young learners

If you are under 18, use Lemmas with a parent or guardian’s knowledge. If you are under 13, a parent or guardian should create and supervise the account. See the Privacy Policy for what is stored and how to have it removed.

Contact

These terms are offered by William Sun and Surya Raghavan, who run Lemmas. Reach them at lemmas.official@gmail.com. Any dispute is governed by the laws of New Jersey, US.