Except where otherwise noted, the notes on this site are © 2026 Yeonsol Kim and licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License (CC BY-NC-SA 4.0). This covers their text and figures and the audio narration made from them.
In short, you may copy, share and adapt the notes, for example in your own notes or in teaching, provided that
- you credit the author, link to the note and to the license, and indicate any changes you made;
- you do not use them for commercial purposes; and
- you share anything you make from them under the same license.
This summary does not replace the legal text of the license. For uses it does not allow, such as commercial use, please ask.
Giving credit
A credit names the note, the author, the source and the license, with links where possible. For example:
“Perfect Sets” by Yeonsol Kim, from External, licensed under CC BY-NC-SA 4.0.
Citing a note
To cite a note in a paper or thesis, treat it as a web page: give the author, title, site, address and the date you accessed it. In BibTeX, for example:
@misc{kim-perfect-sets,
author = {Kim, Yeonsol},
title = {Perfect Sets},
howpublished = {External, \url{https://yeonsolkim.com/...}},
year = {2026},
note = {Accessed 6 October 2026}
}
What the license does not cover
- The mathematics itself. Copyright covers expression, not ideas: the license applies to the way definitions, theorems and proofs are written here, not to the mathematics they express.
- Other people’s work. Material quoted or reproduced from a textbook or another work, listed under References, remains under its own terms.
- The code that builds this site, which is under the MIT License. Fonts and other third-party files in the repository keep their own licenses.