MathOverflow

Long-ago I have written a preprint with some colleagues where we claimed extending the classical Kazdan-Warner trichotomy to the setting where $M$ is a smooth manifold of dimension $\geq 3$ with a effective smooth action by a compact Lie group $G$ assuming...

I am trying to formalize a non-standard algebraic framework to handle singularities (specifically division by zero) not as undefined operations or single points at infinity (like the Riemann sphere or the real projective line), but as a transition to...

Many introductions to category theory brush over size issues (by which I mean paying attention to which categories are small, locally small, dealing with facts like there being no category of all categories, possibly introducing Grothendieck universes...

Is it possible to find an example of a finite separating union-closed family $\mathcal{F}$, with size of the universe $|U(\mathcal{F})| = n$, with a biconnected Hasse diagram graph (without articulation vertices), such that there exist a union of $\lfloor...