MathOverflow Questions, Problems & Solutions : TransWikia.com ~ Page 33

Is there a notion of Čech groupoid of a cover of an object in a Grothendieck site?

Given a topological space $X$, and a cover $mathcal{U} :=cup_{alpha in I}U_{alpha}$ of $X$, one can define a groupoid called Čech groupoid $C(mathcal{U})$ of...

Asked on 01/19/2021 by Adittya Chaudhuri

1 answer

Are universal geometric equivalences of DM stacks affine?

Let $f:Xto Y$ be a map of Deligne-Mumford stacks. Let's say that the map $f$ is a geometric equivalence if the induced map on small étale topoi...

Asked on 01/17/2021 by Harry Gindi

0 answer

Barycentric coordinates of weighted edges

Given $K_n$ with weighted edges, we can fix an edge $e_{AB}$, iterate over all non-adjacent edges $e_{CD}in Esetminus e_{AD}$ and record how often $e_{AB}$ was in...

Asked on 01/17/2021 by Manfred Weis

0 answer

Question on limit in probability of the ratio of max to min of 2 sequences of non-ive, continuous iid random variables with support $[0, infty).$

For each $ m ge 1$, let $X_m$ and $Y_m$ be two non-negative iid random variables with the same distribution. (The distributions of $X_m$ may change...

Asked on 01/16/2021 by Learning math

1 answer

PhD dissertations that solve an established open problem

I search for a big list of open problems which have been solved in a PhD thesis by the Author of the thesis (or with collaboration of her/his supervisor)....

Asked on 01/16/2021

18 answer

Commutant of the conjugations by unitary matrices

Let $mathcal{L}(mathbb{C}^{n times n})$ denote the algebra of all linear mappings from $mathbb{C}^{n times n}$ to $mathbb{C}^{n times n}$ and let $mathcal{C} subseteq mathcal{L}(mathbb{C}^{n times n})$...

Asked on 01/16/2021 by Jochen Glueck

3 answer

Constructing intertwiners between representations of compact quantum groups

Consider the following paper by Van Daele en Maes Notes on compact quantum groups. For convenience of the reader, here is a picture of the relevant section:...

Asked on 01/15/2021

1 answer

A certain property for Heegaard splittings

I've become interested in 3-manifolds with the following property (called 'Property A'): let $c_{i}$ be a set of $g$ curves on a genus $g$ surface $Sigma$...

Asked on 01/15/2021 by no_idea

1 answer

When have we lost a body of mathematics because errors were found?

The history of mathematics over the last 200 years has many occasions when the fundamental assumptions of an area have been shown to be flawed, or even wrong. Yet I...

Asked on 01/14/2021 by Edmund Harriss

10 answer

Prove that there are no composite integers $n=am+1$ such that $m | phi(n)$

Let $n=am+1$ where $a $ and $m>1$ are positive integers and let $p$ be the least prime divisor of $m$. Prove that if $a<p$...

Asked on 01/13/2021 by David Jones

1 answer

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