Matt N.

15,220 reputation

32170

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Fundamenta Mathematicae.

Biblioteka Wirtualna Matematyki.

	15,220 reputation	bio	website		visits	member for	2 years, 4 months
32170 badges		location			seen	May 15 at 15:06

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428 Questions

views newest activity votes

votes

answers

497

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$H_0(X,A) = 0 \iff A \cap X_i \neq \emptyset \forall $ path-components $X_i$

algebraic-topology

nov 10 at 5:16 BenjaLim 16.6k

votes

answers

496

views

Neatest proof that set of finite subsets is countable?

elementary-set-theory set-theory

apr 14 at 22:33 N. S. 27.3k

votes

answers

475

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A question regarding normal field extensions and Galois groups

abstract-algebra field-theory galois-theory

feb 17 '11 at 21:54 Arturo Magidin 158k

vote

answers

472

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Proof that every finite dimensional normed vector space is complete

normed-spaces

feb 15 at 19:33 0x90 281

vote

answer

469

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Proof: A loop is null homotopic iff it can be extended to a function of the disk

algebraic-topology

jun 24 '11 at 13:32 Jason DeVito 14.2k

votes

answer

467

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Characterisation of compact subsets of Banach spaces

homework general-topology functional-analysis

jan 9 '12 at 20:24 Matt N. 15.2k

votes

answer

450

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Klein bottle homology by Mayer Vietoris

algebraic-topology

aug 21 '11 at 17:36 Alexander Thumm 3,236

votes

answers

449

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Example of application of the Uniform Boundedness Principle

functional-analysis examples-counterexamples

aug 19 at 17:04 Matt N. 15.2k

votes

answers

436

views

Deformation retract on path-connected space

algebraic-topology

mar 9 '11 at 16:35 Alex 275

votes

answers

434

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Reduced homology

algebraic-topology

aug 8 '11 at 3:54 Sean Tilson 2,433

vote

answer

433

views

2 step Runge Kutta method with parameter $\Theta$

numerical-methods

jan 27 '11 at 11:59 Jitse Niesen 858

votes

answer

427

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Radon Nikodym derivative proof

homework measure-theory functional-analysis

apr 11 at 2:57 Community♦ 1

vote

answers

421

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Bijection between ideals of $R/I$ and ideals containing $I$

abstract-algebra ring-theory

oct 4 '11 at 3:54 Arturo Magidin 158k

votes

answer

416

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Homology of disjoint union is direct sum of homologies

algebraic-topology

aug 8 '11 at 20:19 Agustí Roig 8,060

votes

answers

413

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A question about regularity of Borel measures

measure-theory

may 15 at 17:50 savick01 1,180

vote

answers

405

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Minimal polynomials

abstract-algebra field-theory

feb 13 '11 at 20:57 Arturo Magidin 158k

vote

answers

402

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Homology of $\mathbb{R}^3 - S^1$

algebraic-topology

aug 14 '11 at 17:06 Andrea 2,970

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answers

398

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Examples of $X$ such that $\pi_1(X) $ not abelian?

algebraic-topology

aug 3 '11 at 19:10 Grigory M 6,842

votes

answer

398

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Base and subbase of a topology

general-topology

apr 28 '12 at 16:57 countinghaus 6,092

votes

answers

379

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Question about the Riesz representation theorem(s)

functional-analysis measure-theory

aug 16 at 18:19 tomasz 6,894

votes

answers

373

views

Understanding the trivialisation of a normal bundle

algebraic-topology vector-bundles fiber-bundles

sep 11 at 19:10 Matt N. 15.2k

votes

answers

370

views

Example of Artinian module that is not Noetherian

commutative-algebra modules

feb 22 at 14:27 AmirHosein SadeghiManesh 850

votes

answers

359

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A question about the nilradical

abstract-algebra ring-theory

oct 6 '11 at 22:54 Zev Chonoles♦ 53k

vote

answer

353

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Why is a finite CW complex compact?

algebraic-topology

apr 21 '11 at 10:23 Thomas Rot 2,081

votes

answers

343

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Homology of Euclidean space $H_n(\mathbb{R}^m)$

algebraic-topology

aug 14 '11 at 9:05 Matt N. 15.2k

votes

answers

328

views

Question about example of non-separable Hilbert space

functional-analysis hilbert-spaces

aug 2 at 16:17 Matt N. 15.2k

votes

answers

327

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Inner product is jointly continuous

functional-analysis inner-product-space

jul 24 at 15:03 Matt N. 15.2k

votes

answers

322

views

Proof that $\frac{S_n}{n}$ converges almost surely to $\mu$

probability

feb 11 '11 at 17:26 Byron Schmuland 15.3k

votes

answer

310

views

Proof that every normed vector space is a topological vector space

normed-spaces norm topological-vector-spaces

jul 7 at 17:52 Matt N. 15.2k

votes

answer

305

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Open problems in Algebraic Topology, Geometric Topology and related fields

reference-request algebraic-topology

sep 2 at 10:59 Akhil Mathew 16.2k