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JHF
  • Member for 9 years, 7 months
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12 votes

there is no 3-manifold such its fundamental group is isomorphic to direct product Z⊕Z⊕Z⊕Z.

10 votes

How to find root subgroups

10 votes

Calculate the cohomology group of $U(n)$ by spectral sequence.

8 votes
Accepted

The first Stiefel-Whitney class is zero if and only if the bundle is orientable

8 votes
Accepted

Product in category of cyclic groups.

7 votes

Immersions of vector bundles

7 votes
Accepted

Understanding Adams spectral sequence and Pontryagin-Thom isomorphism intuitively

7 votes

Finite dimensional CW complex $X$ other than wedge of two spheres so that $\tilde{H}(X) \approx \mathbb{Z} \oplus \mathbb{Z} $

6 votes

Why is the category of simplicial sets closed under finite inductive limits and projective limits?

5 votes
Accepted

Spectral realization of the natural transformation from bordism to singular homology

5 votes
Accepted

Criteria of a real vector bundle to be Stably trivial

5 votes
Accepted

Why are spherical objects so named?

5 votes
Accepted

Orbit space of torus homeomorphic to mobius strip

5 votes
Accepted

Show that every continuous map $f:M\longrightarrow M$ which is homotopic to the identity has a fixed point

5 votes

The difference between weak Kan complexes and Kan complexes

5 votes

How to visualise $\mathcal{O}(1)$ on $\mathbb{P}^1$

5 votes

Motivation of Stone–Čech compactification

5 votes
Accepted

The Stiefel-Whitney classes of a tangent bundle as a manifold

5 votes
Accepted

Spaces with only even dimensional cells has zero $K^{-1}$ group?

4 votes
Accepted

$g$-holed torus identification

4 votes

Example of a space whose complex K-theory is not easily computable from singular cohomology

4 votes
Accepted

understanding construction and definition of classifying space BG

4 votes
Accepted

Existence of specific sections of vector bundles over a manifold

4 votes
Accepted

Bott Periodicity of Class Group: Linkage to $K$-theory

4 votes
Accepted

Fundamental group of $S^1\vee S^1$

4 votes
Accepted

Degree theory of rational fractions over $ \mathbb{C} $.

4 votes
Accepted

fibrations and map of spectral sequences.

4 votes
Accepted

Is there $(X,\mathcal{T})$ contractible, $\mathcal{T}'\subseteq\mathcal{T}$ such that $(X,\mathcal{T}')$ isn't contractible?

4 votes
Accepted

Question about proof of theorem 3.16. (page 219,220 and 221 ) in Hatcher

4 votes
Accepted

Hirzebruch's $L$-polynomial and $\mathbb{C}P^n$

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