Simon Rose

Sweden

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What are the benefits of viewing a sheaf from the "espace étalé" perspective?

ag.algebraic-geometry sheaf-theory ct.category-theory asked May 7, 2012 at 21:01

mathoverflow.net

50 votes

What is the purpose of the flat/fppf/fpqc topologies?

ag.algebraic-geometry grothendieck-topology asked Jan 29, 2015 at 10:33

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32 votes

Is there a nice explanation for this curious fact about cyclic subgroups?

nt.number-theory gr.group-theory finite-groups abelian-groups p-groups asked Jun 3, 2016 at 9:43

mathoverflow.net

21 votes

How many ways can I factor a matrix (over $\mathbb{Z}$)?

matrices algebraic-groups arithmetic-groups asked Mar 29, 2016 at 14:01

mathoverflow.net

17 votes

How do modular forms of half-integral weight relate to the (quasi-modular) Eisenstein series?

modular-forms theta-function eisenstein-series quasimodular-forms half-integral-weight asked Sep 8, 2010 at 18:28

mathoverflow.net

16 votes

Can one determine the dimension of a manifold given its 1-skeleton?

gn.general-topology manifolds simplicial-complexes triangulations asked Jan 6, 2019 at 19:31

mathoverflow.net

15 votes

How many sporadic simple groups are there, really?

gr.group-theory finite-groups sporadic-groups asked Dec 10, 2013 at 18:02

mathoverflow.net

14 votes

Am I missing something about this notion of Mirror Symmetry for abelian varieties?

ag.algebraic-geometry elliptic-curves abelian-varieties k3-surfaces mirror-symmetry asked Dec 1, 2014 at 12:48

mathoverflow.net

13 votes

What relations exist among (quasi-) modular forms of different levels?

modular-forms nt.number-theory asked Mar 22, 2011 at 22:39

mathoverflow.net

13 votes

Why isn't the orbifold cohomology of $pt/G$ equal to the cohomology of $BG$?

group-cohomology orbifolds classifying-spaces asked Mar 3, 2011 at 0:02

mathoverflow.net

Top Answers

Is there a domain "larger" than (i.e., a supserset of) the complex number domain?

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Intuition behind normal subgroups

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What's the sum of all the positive integral divisors of $540$?

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Prove that the additive groups $\mathbb{Z}$ and $\mathbb{Q}$ are not isomorphic.

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de Rham vs Dolbeault Cohomology

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Is every algebraic $K3$ surface a quartic surface?

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Complex torus, C^n/Λ versus (C*)^n

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Elliptic curves on abelian surface

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What recent discoveries have amateur mathematicians made?

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Examples of "Unusual" Classifications

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Understanding the definition of the quotient stack $[X/G]$

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Identifying the generating function $ G(a,z) = \sum_{n=0}^{\infty} a^n z^{(n+1)(n+2)/2}. $

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Sum $\frac{1}{1\times2}+\frac{1}{1\times3}+\frac{1}{2\times5}+\frac{1}{3\times8}+\cdots$

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Existence of Homomorphism so that Diagram Commutes

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show that $\frac{1}{F_{1}}+\frac{2}{F_{2}}+\cdots+\frac{n}{F_{n}}<13$

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What is the meaning of non-Hausdorff spaces in algebraic geometry

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Blackboard rendering of math fonts

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Given a normal subgroup N⊆G, when does G contain a subgroup isomorphic to G/N?

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What exactly is a dimension?

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Examples for Stone–Čech compactification

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Examples in mirror symmetry that can be understood.

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Triviality of finite fiber bundles

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101102103104105106..............149150? What is the remainder when divided by 9?

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Integral element in $\mathbb{Q}(\sqrt{2})$ over $\mathbb{Z}$ has form $m+n\sqrt{2}$

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What is a branched Riemann surface with cuts?

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How do I evaluate $\int \frac{\mathrm{d}x}{e^x + 1} $?

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Trivial Fundamental Group Notation (1 or 0)

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Meaning of $g_d^r$ in algebraic geometry

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When do homology groups have torsion?

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$\psi$ class in $\overline{M}_{0,n}$

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