Newest Questions
167,963 questions
Score of 0
0 answers
2 views
Prove or disprove the closedness of left(right) semiregular bands
One of the application's of Isbell Zigzag theorem is to prove the semigroups closed in itself. Using Zigzag theorem, it has been already proved closedness in itself for all sub-bands classified by ...
Score of -3
0 answers
56 views
A Possible New Theorem in Plane Geometry: Characterizing the Barycenter by Geometric Progression [closed]
Theorem: Characterization of the barycenter by geometric progression
Setting and hypotheses. Let $A$ and $B$ be two distinct points of the plane $\mathcal{P}$, let $\alpha \in \mathbb{R}$, and let $k \...
Score of -4
0 answers
46 views
A Completely New Analysis of the Nautilus and Spirula spirula [closed]
I would like to share with you what I believe is a completely new approach to the analysis of the spiral structures of the Nautilus and Spirula Spirula shells.
My aim was to investigate whether these ...
Score of 5
1 answer
193 views
Exponent of $\mathrm{SL}_n(\mathbb F_q)$ and its semisimple part
Let $q=p^f$, and let $n\ge2$. I am studying the exponent of $\mathrm{SL}_n(\mathbb F_q)$ as part of a more general problem concerning linear groups over finite local rings.
For $\mathrm{GL}_n(\mathbb ...
Score of 0
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105 views
Can a finite arrangement of plane mirrors create the illusion of an intact building?
In the Colombian film masterpiece La estrategia del caracol (directed by Sergio Cabrera), Jacinto, an old Spanish anarchist and intellectual, designs an ingenious optical illusion. He places a large ...
Score of 3
1 answer
74 views
Strong continuity of $\Gamma_!$ for locally rigid proper categories
Let $C$ be a locally rigid proper category over, say, the category $Sp$ of spectra. It is self-dual and proper, so it has a strongly continuous evaluation functor $\mathrm{ev}: C\otimes C\to Sp.$ This ...
Score of 7
2 answers
146 views
Quantum $\operatorname{SU}(2)$ and the $6$ vertex model
The standard $R$-matrix that gives the quantum matrices $M_q(2)$ (which quotient to give Woronowicz's $\operatorname{SU}_q(2)$) is given by
$$
R^{ij}_{kl} = q^{\delta_{ij}} \delta_{ik}\delta_{jl} + (q-...
Score of 14
1 answer
460 views
Which topos (or topoi) most accurately reflect Brouwer's ideas on intuitionism?
Let me first clarify that I am not expecting the titular question to have a single well-defined answer (or it would probably have to be a useless one like “the topos freely generated by the following ...
Score of 6
2 answers
370 views
Question about three consecutive prime numbers
Let $a$, $b$, and $c$ be three consecutive prime numbers. Does the following inequality always hold? $(c-b)(b-a) < a+b+c$
Score of 0
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29 views
Cycle structure and pattern probabilities for the product of two overlapping random $k$-cycles
Fix $k\ge 1$ and let $\sigma,\tau$ be independent uniformly random $k$-cycles on a common ground set of size $N=2k-m$, chosen so that $|\mathrm{supp}(\sigma)\cap\mathrm{supp}(\tau)|=m$ exactly (...
Score of 3
1 answer
185 views
Can we tile the plane with mutually similar and mutually non-congruent copies of some polygon that is not itself a tile?
Ref 1: Tiling with similar tiles
Ref 2: Tiling the plane with pair-wise non-congruent and mutually similar triangles
Ref 3: Tiling the plane with pair-wise non-congruent and mutually similar ...
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55 views
Can $MI_n\setminus x_n$ be represented by a fixed three-dimensional quotient construction for every $n \ge 0$?
Fix an integer $n\ge 0$. Let $X,Y,Z$ be pairwise disjoint sets of size
$n+1$, also disjoint from $\{1,2,3,4\}$, and put
$$
E_n=\{1,2,3,4\}\sqcup X\sqcup Y\sqcup Z,
\qquad r=n+3.
$$
Define
$$
\begin{...
Score of 2
0 answers
84 views
Extremal monomorphisms do not have to be strong
$\newcommand{\id}{\mathrm{id}}$I would like to know examples of extremal monomorphisms that are not strong monomorphisms. Of course, by duality, this is equivalent to finding examples of extremal ...
Score of 2
0 answers
106 views
Understanding the maximal parahoric subgroups of special unitary groups
$\DeclareMathOperator\SU{SU}$In Section 3.11 of "Reductive groups over local fields" (Tits 1979), Tits explicitly describes representatives for the $2$ conjugacy classes of maximal parahoric ...
Score of 1
2 answers
200 views
What is the strength of the set of all translations provable by ZFC to satisfy a model of TSTI?
Let $\cal M$ be a model of the Theory of Simple Types with Infinity "$\sf TSTI$" constructed via $\sf ZFC$, in the sense that there is a syntactic injective map $\tau$ (we call it a '...