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Any binary relation $R\subseteq X\times Y$ gives rise to a Galois connection between the powersets of $X$ and $Y$ in a well known way (on MO you can see it e. g. in this answer; in fact, such Galois c …

I mean the extremely useful literature list compiled by Nora Ganter. One of the entries there is Segal: Bourbaki and the long version of the Bourbaki article What I know is the version on numdam (El …

This question arose from another one of mine, Homotopy type of some lattices with top and bottom removed. An element $d$ of a bounded lattice $L$ is called $\mathit{dense}$ if $$ \forall x\in L\ (d\l …

Most surely I will tag this by reference request: I am sure very much is known about this question, I am just too ignorant to even guess where to look. What makes me feel especially foolish is the sus …

Consider the minimal normal modal logic $K$ (axioms = classical propositional logic + $(\Box(p\land q)\leftrightarrow\Box p\land\Box q)$ + $(\Box\top)$, nothing else). Its canonical model with no var …

Motivation - I was thinking about calculating the integrals from An interesting integral expression for $\pi^n$? using old plain Riemann sums. There, one needs integrating over that part of $[0,1]^n$ …

This question obviously applies to not only mathematics, so maybe I should post it on academia.SE or somewhere else; but then again, mathematical literature has its own specifics related to existing s …

Actually I came upon this through MO a couple of days ago: in here (http://aimath.org/aimnews/lmfdb/) there is a mesmerizing image The caption reads A Maass form, one of the 20 different types of ob …

This is sort of a spinoff of Is there a useful generalization of the Schmidt decomposition to the tensoring together of 3 or more vector spaces? - seems to be almost hopeless, but maybe some partial r …

This question might be too lightweight here but on math.SE it did not receive any feedback since May 2, so... Polarization works both ways. Not only can you represent any homogeneous polynomial $f$ of …

(By request from a comment: UF stands for Univalent Foundations) Correct me if I'm wrong, but in a model $M$ of ZF each element $x$ of $M$ should produce a directed-graph-with-a-marked-sink $G_x$ havi …

Let $D\xrightarrow[]\varphi D\xrightarrow[]kE\xrightarrow[]j\Sigma D$ be an exact triangle in a triangulated category. I am trying to figure out what structure emerges from this on the base of the axi …

There are (at least) two variants of this question. Is it possible to modify the axioms of set theory, without arriving at obvious contradiction, in such a way that in a model of the theory there is …

What I definitely remember is that I saw a description of the following in the Bulletin of the American Mathematical Society, sometime in eighties (or maybe nineties?) One considers the group generate …

I've posted this to Math.SE about a month ago: Seems like $$ \Delta(a_0+a_1t^d+a_2t^{2d}+...+a_nt^{nd})=(-1)^{n\frac{d(d-1)}2}d^{nd}(a_0a_n)^{d-1}[\Delta(a_0+a_1t+a_2t^2+...+a_nt^n)]^d, $$ where $\De …