User Hulkster

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The definition of Determinant in the spirit of algebra and geometry

Sep 19 '19 at 10:55 Hulkster 1

5

11

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2

answers

664

views

$\sum\limits_{i=1}^n \frac{x_i}{\sqrt[n]{x_i^n+(n^n-1)\prod \limits_{j=1}^nx_j}} \ge 1$, for all $x_i>0.$

algebra-precalculus inequality summation contest-math holder-inequality

Jul 27 at 18:51 Michael Rozenberg 177k

1

10

votes

1

answer

531

views

Topological Open Mapping Theorem for mappings between different Euclidean dimensions?

general-topology analysis multivariable-calculus reference-request differential-topology

Sep 17 '19 at 22:02 Hulkster 1

5

7

votes

8

answers

1k

views

Most natural intro to Complex Numbers [closed]

complex-numbers education

Dec 3 '15 at 15:49 Gewure 173

6

votes

2

answers

460

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Prove that $\sum_{i=1}^n\frac{x_i}{\sqrt[nr]{x_i^{nr}+(n^{nr}-1)\prod_{j=1}^nx^r_j}} \ge 1$ for all $x_i>0$ and $r \geq \frac{1}{n}$.

algebra-precalculus inequality summation conjectures

Aug 9 at 16:31 Xander Henderson♦ 21.6k

5

6

votes

2

answers

2k

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Is simple closed curve homeomorphic to a circle?

general-topology algebraic-topology plane-curves

Mar 3 '17 at 3:55 user421813 1

2

5

votes

2

answers

141

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Nonexistence of a continuous injection $f:S^2 \rightarrow \mathbb{R^2}$

analysis algebraic-topology differential-topology

Jul 5 '16 at 15:56 Mark Fischler 40.1k

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votes

0

answers

108

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Generalization of FTA

general-topology complex-analysis analysis complex-numbers

Mar 29 '16 at 4:23 Michael 18k

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votes

1

answer

660

views

Winding number integral/index in plane

analysis multivariable-calculus differential-topology vector-analysis winding-number

Feb 11 '15 at 9:54 Hulkster 1

3

votes

1

answer

150

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If $n>m$, then the spheres $S^n$ and $S^m$ are not homeomorphic?

general-topology algebraic-topology differential-topology

Feb 6 '19 at 18:10 Angina Seng 150k

2

3

votes

1

answer

632

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Fundamental Theorem of Algebra - an elementary complex analysis proof?

complex-analysis analysis alternative-proof complex-integration

Aug 9 '17 at 0:47 Hulkster 1

3

votes

2

answers

353

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Topological disk doesn't separate the plane

general-topology reference-request algebraic-topology

Aug 17 '16 at 8:40 Aloizio Macedo♦ 30.5k

3

votes

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answer

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Ham Sandwich Theorem - intuitive proof

general-topology differential-geometry algebraic-topology soft-question

Jul 27 '16 at 19:00 Lee Mosher 82.9k

3

votes

1

answer

81

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Anatomy of $\mathcal P(\mathbb{N})$

elementary-set-theory cardinals

Aug 21 '15 at 15:02 hmakholm left over Monica 269k

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votes

1

answer

55

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A Weak Schönflies Theorem in $\mathbb{R^n}$?

general-topology analysis reference-request algebraic-topology conjectures

Jan 29 '20 at 0:03 Hulkster 1

1

2

votes

1

answer

155

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A wild knot and its complement

algebraic-topology soft-question knot-theory low-dimensional-topology

Jan 28 '20 at 2:55 Hulkster 1

1

2

votes

1

answer

68

views

Differentiating under the integral sign and $C^1$ class

calculus real-analysis analysis multivariable-calculus

Dec 14 '17 at 19:45 David C. Ullrich 78.6k

1

2

votes

1

answer

153

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Null-homotopic closed curve in a Jordan domain [duplicate]

real-analysis general-topology analysis algebraic-topology

Aug 26 '17 at 7:47 Hulkster 1

2

votes

1

answer

553

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Borsuk-Ulam Theorem, an intuitive proof.

general-topology differential-geometry algebraic-topology soft-question differential-topology

Mar 31 '17 at 3:44 Community♦ 1

2

votes

0

answers

199

views

2D Brouwer fixed point theorem

general-topology reference-request

Feb 20 '16 at 3:34 Hulkster 1

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2

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2

answers

241

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Sequence of points that is dense in a compact set.

notation

Feb 12 '16 at 1:54 Tsemo Aristide 81.3k

2

votes

1

answer

264

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Jordan curve theorem and connectedness.

real-analysis general-topology connectedness

Sep 26 '15 at 4:58 Henno Brandsma 197k

1

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votes

1

answer

285

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Mapping degree of a diffeomorphism

differential-geometry differential-topology

Feb 2 '15 at 15:57 Thomas Rot 9,094

1

vote

3

answers

707

views

Index of a Jordan curve

general-topology complex-analysis differential-topology plane-curves winding-number

Oct 9 at 18:00 John Hughes 84.6k

1

vote

1

answer

124

views

Alexander Duality Theorem, a simple version in $\mathbb{R}^n$

general-topology algebraic-topology

Aug 3 '19 at 14:01 Paul Frost 43k

1

vote

1

answer

86

views

Subdivision of a simple polygon into triangles? [duplicate]

combinatorics graph-theory reference-request plane-curves plane-geometry

Feb 1 '18 at 10:13 Hulkster 1

1

vote

2

answers

322

views

Boundary of a general plane domain?

general-topology algebraic-topology plane-curves

Jan 11 '18 at 11:31 M. Winter 26.4k

1

vote

1

answer

1k

views

Fourier transform and expectation values in QM?

probability multivariable-calculus fourier-transform quantum-mechanics

Sep 19 '17 at 18:41 Hulkster 1

2

1

vote

1

answer

460

views

Fundamental theorem of Algebra from the Brouwer fixed point theorem.

general-topology analysis proof-verification polynomials algebraic-topology

Aug 13 '17 at 3:09 Community♦ 1

1

vote

1

answer

239

views

Path integral over fractal

integration complex-analysis contour-integration fractals winding-number

Aug 10 '16 at 10:51 Hulkster 1

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49 Questions

The definition of Determinant in the spirit of algebra and geometry

$\sum\limits_{i=1}^n \frac{x_i}{\sqrt[n]{x_i^n+(n^n-1)\prod \limits_{j=1}^nx_j}} \ge 1$, for all $x_i>0.$

Topological Open Mapping Theorem for mappings between different Euclidean dimensions?

Most natural intro to Complex Numbers [closed]

Prove that $\sum_{i=1}^n\frac{x_i}{\sqrt[nr]{x_i^{nr}+(n^{nr}-1)\prod_{j=1}^nx^r_j}} \ge 1$ for all $x_i>0$ and $r \geq \frac{1}{n}$.

Is simple closed curve homeomorphic to a circle?

Nonexistence of a continuous injection $f:S^2 \rightarrow \mathbb{R^2}$

Generalization of FTA

Winding number integral/index in plane

If $n>m$, then the spheres $S^n$ and $S^m$ are not homeomorphic?

Fundamental Theorem of Algebra - an elementary complex analysis proof?

Topological disk doesn't separate the plane

Ham Sandwich Theorem - intuitive proof

Anatomy of $\mathcal P(\mathbb{N})$

A Weak Schönflies Theorem in $\mathbb{R^n}$?

A wild knot and its complement

Differentiating under the integral sign and $C^1$ class

Null-homotopic closed curve in a Jordan domain [duplicate]

Borsuk-Ulam Theorem, an intuitive proof.

2D Brouwer fixed point theorem

Sequence of points that is dense in a compact set.

Jordan curve theorem and connectedness.

Mapping degree of a diffeomorphism

Index of a Jordan curve

Alexander Duality Theorem, a simple version in $\mathbb{R}^n$

Subdivision of a simple polygon into triangles? [duplicate]

Boundary of a general plane domain?

Fourier transform and expectation values in QM?

Fundamental theorem of Algebra from the Brouwer fixed point theorem.

Path integral over fractal