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Homotopy theory, homological algebra, algebraic treatments of manifolds.

38 votes
3 answers
8k views

The error in Petrovski and Landis' proof of the 16th Hilbert problem

What was the main error in the proof of the second part of the 16th Hilbert problem by Petrovski and Landis? Please see this related post and also the following post.. For Mathematical development …
Ali Taghavi's user avatar
24 votes
2 answers
2k views

Periodic orbit property

A topological space $X$ satisfies the "Periodic orbit property", briefly POP, if for every continuous map $f:X \to X$, there exist a natural number $n$ and a point $x_{0}\in X$ such that $f^{n}(x_{ …
Ali Taghavi's user avatar
15 votes
1 answer
595 views

An equivariant map from sphere to a Lie group of lower dimension which is not null homotopic?

Is there a natural number $n$, a compact Lie group $G$ of dimension less than $n$ and a continuous map $f:S^n \to G$ with $f(-x)=f(x)^{-1}$, such that $f$ is not a null homotopic map? This quest …
Ali Taghavi's user avatar
15 votes
0 answers
715 views

Is this "Homology" useful to study?

In the usual singular homology of a topological space $X$, one consider the free abelian group generated by all continuous maps from the standard simplex $\Delta^{n}$ to $X$. Now we can r …
Ali Taghavi's user avatar
14 votes
1 answer
458 views

A parametric version of the Borsuk Ulam theorem

Is there a topological space $X$, which is not a singleton, and satisfies the following property? For every continuous function $f: X\times S^2\to\mathbb{R}^2$ there exist a point $x\in S^2$ such th …
Ali Taghavi's user avatar
12 votes
2 answers
555 views

Restriction of "$\pi_{1}$" to topological groups

Let $G$ and $H$ be two topological groups. Assume that $\phi:\pi_{1}(G) \to \pi_{1}(H)$ is a group homomorphism. Is there a continuous function $f:G\to H$ such that $f_{*}=\phi$?
Ali Taghavi's user avatar
12 votes
3 answers
851 views

A nontrivial principal bundle which satisfies Leray-Hirsch theorem

What is an example of a nontrivial principal bundle whose fibre space $G$, total space $P$ and base space $M$ are compact connected manifolds (the fiber $G$ is a compact Lie group) such that $$H^*(P,\ …
Ali Taghavi's user avatar
10 votes
1 answer
543 views

An equivariant social choice in Mathematical economics

Motivated by this paper and its economics motivations, we recall that a social choice among $n$ objects is a continuous function $$f:\overbrace{M\times M\times\cdots\times M}^{\text{$n$ times}}\to …
Ali Taghavi's user avatar
10 votes
1 answer
385 views

A symmetric embedding of manifolds

Assume that $M$ is a manifold. Is there an embedding of $M$ in some $\mathbb{R}^{n}$ such that the image of $M$ in $\mathbb{R}^{n}$ is invariant under each reflection $(x_{1},x_{2},\ldots x_{i},\l …
Ali Taghavi's user avatar
9 votes
2 answers
619 views

Can we foliate the punctured space by tori?

Is it possible to have a 2 dimensional foliation of $\mathbb{R}^{3}-\{0\}$ such that each leaf is homeomorphic to the torus? what algebraic topological obstruction exist? Another question: is there …
Ali Taghavi's user avatar
9 votes
2 answers
922 views

A question on fixed point theory

I asked this question in MSE, but I did not received any answer, so I repeat it here: https://math.stackexchange.com/questions/858238/a-question-on-fixed-point-property Assume that $0<k<n-1$, Note …
Ali Taghavi's user avatar
8 votes
2 answers
476 views

A property stronger than the fixed point property

Assume that $X$ is a topological space. We say that $X$ satisfies the strong fixed point property if the graph of every surjective continuous self-map intersect the graph of every continuous self-ma …
Ali Taghavi's user avatar
7 votes
2 answers
305 views

Homotopicity of two certain sections of frame bundle of $GL(n,\mathbb{R})$

Edit: According to comment of Prof. GoodWillie we revise the question. Put $M=GL(n,\mathbb{R})$. We identify $M_n(\mathbb{R})$ with $\mathbb{R}^{n^2}$: The identification is based on the lexicograph …
Ali Taghavi's user avatar
7 votes
0 answers
373 views

Obstructions for existence of a fiber wise covering space structure( A bundle of covering sp...

Let $S^n \times \mathbb{T}^n$ be the trivial Torus bundle over $S^n$. Assume that we have a continuous fiber preserving map $\phi :TS^n \to S^n \times \mathbb{T}^n$ which restriction to each fiber giv …
Ali Taghavi's user avatar
7 votes
0 answers
277 views

A cohomology associated to a vector field on a Riemannian manifold

Edit: Accoring to the comment of Asura Path I revise the question. Let $X$ be a vector field on a Riemannian manifold $(M,g)$. So we have a $1$-form $\beta$ with $\beta(Y)=\langle Y,X\rangle …
Ali Taghavi's user avatar

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