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What's the probability that two numbers share the same totient function value?

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so-called friend Don
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11 votes
3 answers
806 views

Computationally inspired theorems and conjectures in knot theory

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Ian Agol
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11 votes
1 answer
884 views

Primes whose squares add up to another square

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Maxime Jaccon
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1 answer
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Can a category without any nontrivial finite products admit group objects?

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David E Speyer
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1 answer
501 views

Irreducible representations of $S_n$

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Sean Eberhard
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Accumulation points of $(3^n)$ in ${\bf Z}_2$

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Emil Jeřábek
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Is every set of cardinals bounded?

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Elliot Glazer
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3 answers
549 views

When does a smooth $\mathrm{SO}(n)$-action extend to an $\mathrm{O}(n)$-action?

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Will Sawin
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3 answers
413 views

Cardinal arithmetic inequalities according to ZF

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KP Hart
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2 answers
864 views

Metamathematical/philosophical understanding of the smallest aleph

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Mikhail Katz
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16 votes
1 answer
312 views

Can every Sidon set of size 3 be extended to a finite perfect difference set?

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Will Sawin
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748 views
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Can Lebesgue's differentiation theorem fail almost everywhere?

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Saúl RM
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667 views

Which conjectures have been solved (or partially solved) using entropy methods?

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Carl Schildkraut
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451 views

Does every reduced ring inject into a von Neumann regular one, constructively?

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darij grinberg
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6 votes
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534 views

Extension of definition of distance

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Emil Jeřábek
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6 votes
2 answers
499 views

Result seemingly quoted from SGA

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David Roberts♦
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15 votes
1 answer
381 views

Chains of nulls sets: on a question of Elkies (sort of)

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Will Brian
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201 views

Power set of a (Grothendieck) Galois extension

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Will Sawin
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140 views

Relation between completions of $U_q(\mathfrak{sl}_2)$

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Adrien
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405 views

Direct sum and tensor product

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Iosif Pinelis
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377 views

When is the Yoneda extension fully faithful?

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varkor
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Are there higher amorphous sets in the determinacy world?

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TLo
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165 views

Etale cohomological dimension of affinoid perfectoid spaces for $\ell$-torsion sheaves ($\ell \ne p$)

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D.-C. Cisinski
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168 views

Do we have Beilinson type resolution of partial diagonals?

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abx
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288 views

A universal ordering on the sets in a (Turing) degree

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Farmer S
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3 votes
1 answer
360 views

About Cohen forcing

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J. W. Tanner
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280 views

Relationship between Shimura varieties and the moduli stack of principal bundles on a curve

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Will Sawin
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1 answer
265 views

Cancellation in stable infinity-categories

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Tim Campion
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182 views

A universal additive complement

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Peter Mueller
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1 answer
294 views

Partitions of R into meager/measure zero sets

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TLo
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8 votes
1 answer
255 views

Patterns in group cohomology for Abelian groups

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Denis T
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1 answer
149 views

When is $\Theta$ a (weakly) Lowenheim-Skolem cardinal?

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Asaf Karagila♦
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1 answer
188 views

Is Street's nerve fully faithful?

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Thorgott
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1 answer
146 views

When is a $< \kappa$-support iteration of $< \kappa$-closed, $\kappa^+$-cc forcings also so?

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Pedro Marun
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1 answer
297 views

Question on Cohen forcing

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YCor
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1 answer
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Is $ H= (-\Delta)^{\alpha/2} + (X^2)^{\beta/2}$, $\frac{1}{\alpha}+\frac{1}{\beta} = 1$ a quantum harmonic oscillator?

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Carlo Beenakker
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4 votes
1 answer
220 views

Gluing topological spaces

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Mohammad Golshani
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1 answer
198 views

On the quantum SL(2) group

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Ivan Chen
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1 answer
246 views

Probability measures on a non-separable space

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Dano
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2 answers
186 views

Recurrence for a sequence defined by an algebraic generating function

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Somos
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1 answer
234 views

Colimit of parallel morphisms in stable $\infty$-categories

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Ivan Chen
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1 answer
221 views

Is $\mathbb{Z}_{>0}$ diophantine in $(\mathbb{Q}_{>0},+,\cdot,1)$?

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Matt F.
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0 answers
281 views

How close is the "bioctonionic projective plane" to an actual projective plane?

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John C. Baez
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3 votes
1 answer
218 views

A new generalization of Euler product formula?

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Asad Fahd
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262 views
+100

Combinatorial interpretation of q-Narayana numbers for q=-1

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Johann Cigler
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1 answer
153 views

Rings for which every module of projective dimension at most 1 is projective

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Jeremy Rickard
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1 vote
1 answer
224 views

On properties of quotients on the form $G \rightarrow G/H$ for $H \subseteq G$ a closed subgroup scheme

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Jason Starr
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5 votes
0 answers
287 views

What is the inertia-Deligne group?

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MiniQuiff
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