Let $f:\mathbb{CP}^n\to\mathbb{CP}^n$ be a holomorphic map; I am interested in what the subvariety of critical points could be. More specifically, let $J=\{p\in \mathbb{CP}^n\ :\ \det\mathrm{Jac}(f)=0\}$: can $J$ be a smooth submanifold of $\mathbb{CP}^n$? can $J$ be an irreducible subvariety of...

I'm editing Is there a canonical map from the cohomology of orbifold Chiral de Rham on an orbifold to the cohomology of Chiral de Rham on a crepant resolution? as there was a broken arXiv Front link (and I took the opportunity to add some paper titles in). But I cannot submit the edit as the ques...

This question about disc projections has a link to an animation of a Reuleaux triangle spinning inside a square. "That sounds cool, I want to see what that looks like!", I thought. Unfortunately, the link was dead, but through the internet archive I was able to track down the original animation, ...

I tried to edit an old question and when I hit Save Edits it showed me this error, even though I didn't touch the title. Is there a new constraint, and if so, how can one possibly edit an old question without changing (shortening) its title?

In the database the title is 250 characters, so somewhere back in the day the titles were longer. The limit is now 150. That hurts when you edit an old question from before the limit was lowered. You have no other option than to edit the title, maybe salvaging relevant info by moving it in the bo...

I'd need to analyze existing question title length to get a sense of what the maximum length should be. Suggestion of "one line". This of course varies per font and characters used, but for this post it is: Length limit for question titles that have nothing to do with Unicorns (we don’t reall...