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Homotopy theory, homological algebra, algebraic treatments of manifolds.

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
2 votes
0 answers
127 views

Dividing a n- cochain by a 1-cochain

Assume that $X$ is a path connected hausdorff topological space. Let $\alpha\in C^{1}(X,\mathbb{R})$ and $\beta\in C^{n}(X,\mathbb{R})$ be cochains in real singular cohomology. Asume that $\alpha \s …
Ali Taghavi's user avatar
0 votes
1 answer
94 views

Fixed point property for the projectivization of manifold of fixed rank matrices

Let $M$ be the manifold of all matrices in $M_{n}(\mathbb{R})$ with fixed rank $0<k<n$. The projectivization of $M$ is denoted by $PM$. Does $PM$ satisfy fixed point property?
Ali Taghavi's user avatar
3 votes
1 answer
423 views

A weak fixed point property for Grassmannian

Let $f$ be a continuous function on complex Grassmannian $G(k, 2n+1)$. Is it true to say that there is a $k$-plane $Y$ such that $Y$ has nontrivial intersection with $f(Y)$? A motivation for …
Ali Taghavi's user avatar
3 votes
1 answer
206 views

Cohomologically minimal spaces

Let $X$ be a compact connected Hausdorff topological space. We say $X$ is a cohomologicaly minimal space, briefly CM space, if $X$ satisfies the following property: "For every proper subset $A\ …
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
0 votes
1 answer
652 views

A possible proof of the Borsuk Ulam theorem without "Homology-Cohomology"

Assume that $n>1$. The configuration space of $S^n$ is defined as follows $$M_n=\{(x,y)\in S^n\times S^n\mid x \neq y\}$$ We have two questions: 1.Is there a continuous function $f:M_n \ …
Ali Taghavi's user avatar
0 votes
1 answer
102 views

Continuous orthogonal preserving maps between projective space

Is there a continuous map $f:\mathbb{C}P^n \to \mathbb{C}P^m$, for some $n>m$ which preserve orthogonality?Namely $x\perp y \implies f(x) \perp f(y) $? If yes, are there two non homotopic …
Ali Taghavi's user avatar
1 vote
0 answers
80 views

Is $Iso(V)$ a deformation retract of $GL(V)$ when $V$ is a finite dimensional linear normed ...

Assume that $V$ is a finite dimensional real or complex normed linear space. Let $Iso(V)\subset GL(V)\subset L(V)$ be the space of linear isometric endomorphisms, invertible endomorphism and li …
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
5 votes
1 answer
567 views

Can an odd map be null homotopic?

Let $G$ be a compact Lie group with invariant measure $\mu$. An odd function is a continuous function, $\phi:G\to \mathbb{C}$, such that $\int_{G} \phi d\mu=0$. An odd map is a continuous map, $f:G\to …
Ali Taghavi's user avatar
5 votes
2 answers
319 views

Can a punctured $\mathbb{C}P^n$ be a retract of a punctured $\mathbb{C}P^{n+1}$?

In this question we consider the standard inclusion of $\mathbb{C}P^{n}\subset \mathbb{C}P^{n+1}$. It is well known that $\mathbb{C}P^n$ is not a retract of $\mathbb{C}P^{n+1}$. What about if we …
Ali Taghavi's user avatar
2 votes
1 answer
338 views

Cohomology with coefficient in a Lie algebra

For a topological space X we can consider the coefficient of singular cohomology in a Lie algebra A. Then we obtain a graded Lie algebra, that is [x,y]=(-1)^i+j-1 [y,x], for homogeneous elemen …
Ali Taghavi's user avatar
1 vote
2 answers
223 views

Retract embedding of $S^{n}$ in its unit tangent bundle

Acording to the comment of Mark Grant and the answer of Ryan Budney, I revise the question: For what even $n$, there is a retract embedding of of $S^n$ in its unit tangent bundle?
Ali Taghavi's user avatar
3 votes

Solving algebraic problems with topology

The following paper and its references contains some algebraic consequences of vector bundle theory. Vakhtang Lomadze, Applications of vector bundles to factorization of rational matrices, Line …

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