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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 …
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 …
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?
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 …
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 $A\ …
12
votes
2
answers
555
views
Restriction of "$\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 $f_{*}=\phi$?
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 \ …
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 …
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 …
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 …
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 …
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 …
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 …
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?
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 …