It is clear from this answer that a specific configuration of four spindles from spindle toruses, have at least three quartic planar slices. What is interesting is that, this configuration of spindles has quartic slices only for a subset of the entire quartic curve, suggesting a possible "extension"

What is Math SE's policy on questions, answers, and comments which are posted in languages other than English? What should I do if I see something written in another language?

This is largely an accessibility issue. Images are not searchable. Whatever you think of the quality of the built-in search engine, or external tools such as approach0, and their ability to find good matches for search terms, they do exponentially worse when the only information is given in ima...

Recall from model theory that two structures are called elementarily equivalent if they satisfy the same first-order sentences. In other words, two structures $\frak A$ and $\frak B$ of the language $\cal L$ are elementarily equivalent (written $\frak A\equiv\frak B$) if $\operatorname{Th}(\frak ...

Here is what to be proven: No perfect non-empty set in $\mathscr{P}(\Bbb{R})$ has strong measure zero. The textbook (Teoría de la Medida, Jaime San Martin Aristegui, section 1.6) suggests the following approach: Suppose that $f\colon [0,1]\to \Bbb{R}$ is a continuous function and $A\subset [0,...

In A Primer on Spectral Sequences (also later published in More Concise Algebraic Topology), J. Peter May describes the Serre Spectral Sequence for any homology theory. To recap, suppose $p\colon E\rightarrow B$ be a fibration with fiber $F$ s.t. $\pi_1(B)$ acts trivially on $F$ (in the homotopic...