Author: Urs Format: MarkdownItexadded two illustrations grabbed from the literature.
Also added more references and on more cases.
<a href="https://ncatlab.org/nlab/revision/diff/fuzzy+funnel/2">diff</a>, <a href="https://ncatlab.org/nlab/revision/fuzzy+funnel/2">v2</a>, <a href="https://ncatlab.org/nlab/show/fuzzy+funnel">current</a>
added two illustrations grabbed from the literature.