Author: varkor Format: MarkdownItexGuitart's webpage appears no longer to be available, so I have replaced the link with a WayBack Machine link.
<a href="https://ncatlab.org/nlab/revision/diff/Ren%C3%A9+Guitart/2">diff</a>, <a href="https://ncatlab.org/nlab/revision/Ren%C3%A9+Guitart/2">v2</a>, <a href="https://ncatlab.org/nlab/show/Ren%C3%A9+Guitart">current</a>
Guitart’s webpage appears no longer to be available, so I have replaced the link with a WayBack Machine link.