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25

votes

3

answers

2k

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What do we learn from the Wronskian in the theory of linear ODEs?

modified 11 hours ago Martin Sleziak 4,062

13

votes

2

answers

787

views

Is there a known condition for partial sums of a decreasing positive sequence to take all values up to the total sum?

real-analysis sequences-and-series

modified 2 days ago Iosif Pinelis 38.3k

6

votes

3

answers

747

views

Are nuclear operators closed under extensions?

reference-request fa.functional-analysis banach-spaces operator-theory nuclear-spaces

modified May 24 at 17:50 M.González 3,205

9

votes

2

answers

441

views

Are compact objects in presheaf categories finite colimits of representables?

ct.category-theory

modified 1 hour ago Matthieu Romagny 3,114

11

votes

1

answer

336

views

SOS polynomials with integer coefficients

ag.algebraic-geometry nt.number-theory ac.commutative-algebra polynomials oc.optimization-and-control

modified 10 hours ago R. van Dobben de Bruyn 14.7k

6

votes

2

answers

555

views

Curvature of nonsymmetric metric tensors?

ag.algebraic-geometry dg.differential-geometry riemannian-geometry curvature differential-graded-algebras

modified yesterday Robert Bryant 79.2k

12

votes

2

answers

351

views

Conceptual explanations of the class numbers for the first few $\mathbb{Q}(\sqrt{p})$ with odd conductor

nt.number-theory algebraic-number-theory elliptic-curves abelian-varieties class-field-theory

modified 1 hour ago GH from MO 71.5k

13

votes

1

answer

476

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gn.general-topology descriptive-set-theory alternative-proof

answered May 25 at 9:55 Wojowu 13.4k

11

votes

2

answers

243

views

Is every finitely-presentable group a finite colimit of copies of $F_2$?

gr.group-theory ct.category-theory

modified yesterday YCor 37.2k

12

votes

1

answer

335

views

Partial sums of $\sum_0^\infty z^n$

cv.complex-variables power-series

modified 2 days ago François G. Dorais♦ 40.5k

0

votes

1

answer

347

views

Mathematics based only on real numbers [closed]

soft-question big-picture

modified May 22 at 23:58 user76284 1,154

6

votes

2

answers

346

views

Action of fundamental group on homotopy fiber

at.algebraic-topology homotopy-theory fundamental-group fibration

modified May 23 at 21:10 skd 4,388

8

votes

2

answers

406

views

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ag.algebraic-geometry reference-request polynomials arithmetic-geometry fields

modified 20 hours ago RP_ 6,274

9

votes

1

answer

451

views

Are all classes Stiefel-Whitney classes?

at.algebraic-topology homotopy-theory stable-homotopy characteristic-classes

answered May 25 at 3:13 Nicholas Kuhn 6,441

5

votes

2

answers

312

views

Translation of Marsden-Weinstein-Meyer into classical mechanics language

reference-request sg.symplectic-geometry

modified yesterday Ben McKay 18.5k

6

votes

1

answer

199

views

Matrix inequality : trace of exponential of Hermitian matrix

linear-algebra matrices inequalities matrix-analysis

modified May 25 at 14:20 Nathaniel Johnston 3,412

6

votes

1

answer

420

views

Which books should I read in order to be prepared to study information geometry?

dg.differential-geometry pr.probability st.statistics textbook-recommendation information-geometry

modified 2 days ago BrickByBrick 171

3

votes

1

answer

297

views

Varieties with everywhere good reduction that are isomorphic over every completion have isomorphic generic fibers

ag.algebraic-geometry ac.commutative-algebra arithmetic-geometry tensor-products completion

answered yesterday Daniel Litt 18.7k

9

votes

1

answer

179

views

hyperbolic quotient of hyperbolic group

reference-request gr.group-theory geometric-group-theory

modified May 25 at 14:30 Derek Holt 30.7k

12

votes

1

answer

276

views

Can a covering space of the $p$-adic disc split over the circle?

ag.algebraic-geometry rigid-analytic-geometry p-adic-hodge-theory

modified 2 days ago SashaP 5,067

7

votes

1

answer

299

views

+50

Size issues (small/large categories) when defining stacks in the Algebraic/differentiable/topological setting

ag.algebraic-geometry dg.differential-geometry ct.category-theory

modified yesterday Praphulla Koushik 3,753

7

votes

1

answer

372

views

+50

Boundedness of total current in electrical network

co.combinatorics pr.probability linear-algebra graph-theory real-analysis

modified 19 hours ago neverevernever 1,333

5

votes

1

answer

157

views

a square root inequality for symmetric matrices?

reference-request linear-algebra inequalities convexity

modified yesterday Mikael de la Salle 6,483

4

votes

1

answer

423

views

A problem on polynomials

cv.complex-variables polynomials

modified yesterday user159888 273

7

votes

2

answers

199

views

Path integral derivation of extended TQFT

mp.mathematical-physics higher-category-theory quantum-field-theory cobordism topological-quantum-field-theory

answered May 25 at 17:59 David Ben-Zvi 19.9k

3

votes

1

answer

140

views

Is there a 4-polytope without 3-gonal and 4-gonal faces, other than the 120-cell?

co.combinatorics mg.metric-geometry discrete-geometry convex-polytopes polytopes

modified May 23 at 17:17 Dmitri Panov 24.3k

2

votes

1

answer

168

views

Solving multilinear equations

reference-request linear-algebra algorithms

modified yesterday Alexi 229

17

votes

0

answers

343

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Semisimplicity for tensor products of representations of finite groups

ag.algebraic-geometry rt.representation-theory algebraic-groups tensor-products

modified yesterday Daniel Litt 18.7k

3

votes

1

answer

155

views

Books on foliations

gt.geometric-topology textbook-recommendation foliations books

answered May 23 at 9:17 guest 76

6

votes

1

answer

119

views

Does a compact Lie group have finitely many conjugacy classes of maximal Abelian Lie subgroups?

lie-groups topological-groups compactness

answered May 23 at 13:15 YCor 37.2k

5

votes

1

answer

118

views

faithful modules over a finite dimensional commutative algebra

linear-algebra ac.commutative-algebra

answered 14 hours ago Hailong Dao 25.7k

6

votes

2

answers

141

views

Reference request: continuity of Cholesky factor

reference-request linear-algebra matrix-analysis

modified May 25 at 12:22 Zorn's Lama 123

4

votes

2

answers

141

views

The correct homotopically relevant notion of ideals of dg-algebras (or $\mathbb E_1$-rings)

ra.rings-and-algebras infinity-categories differential-graded-algebras derived-algebraic-geometry

answered yesterday Liran Shaul 21

2

votes

1

answer

224

views

The operator equation $AB = \lambda BA$ for self-adjoint operators

linear-algebra operator-theory

modified May 25 at 19:42 Matemáticos Chibchas 201

6

votes

1

answer

128

views

Is there a prefix-continuous bijection between finite words and eventually zero words?

co.combinatorics geometric-group-theory combinatorics-on-words

answered yesterday Pierre PC 1,278

4

votes

1

answer

127

views

history of geometric mechanics

riemannian-geometry ho.history-overview connections classical-mechanics

answered 22 hours ago Viktor Blasjo 251

3

votes

1

answer

206

views

Integral convergence implies pointwise

real-analysis integration

modified 2 days ago Willie Wong 23.5k

4

votes

1

answer

154

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+50

Smallest subgroup of unitary group, containing diagonal matrices and a fixed unitary matrix is the whole group

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modified 7 hours ago Mini 91

2

votes

1

answer

151

views

On a particular proof of “if the sharp of every real exists and every club contains a club constructible from a real, then $\delta^1_2 = \omega_2$”

set-theory constructibility

modified May 26 at 16:35 Gabe Goldberg 2,477

-2

votes

1

answer

229

views

Is the 2-dimensional Gauss-Bonnet theorem applicable in higher dimensions? [closed]

dg.differential-geometry riemannian-geometry differential-topology

modified 2 days ago C.F.G 2,535

5

votes

1

answer

206

views

Conjectured primality test for specific class of $N=k \cdot 6^n+1$

nt.number-theory prime-numbers counterexamples elementary-proofs

answered May 26 at 17:09 Max Alekseyev 15.3k

8

votes

1

answer

159

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Union of Schubert cells being affine

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modified 2 days ago imakhlin 2,473

-2

votes

2

answers

158

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Basic research problems references [closed]

reference-request soft-question open-problems journals

answered 2 days ago Ben McKay 18.5k

5

votes

1

answer

191

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Size of a family of sets of $k$-separated functions over $\{0,1,\ldots,n-1\}$

co.combinatorics extremal-combinatorics

modified yesterday Jakub Konieczny 565

0

votes

1

answer

90

views

Two isomorphic reduced group $C^*$-algebras

oa.operator-algebras c-star-algebras

modified 4 hours ago YCor 37.2k

8

votes

0

answers

383

views

Roadmap for Quillen 1

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modified May 25 at 1:18 Quetzalcoatl 632

3

votes

1

answer

83

views

Distance of parametrized skew hermitian exponentials

linear-algebra

modified May 25 at 21:22 Iosif Pinelis 38.3k

2

votes

1

answer

132

views

Curves on a Kahler manifold

ag.algebraic-geometry complex-geometry

answered May 23 at 3:28 Hacon 1,867

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