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The study of differentiable manifolds and differentiable maps. One fundamental problem is that of classifying manifolds up to diffeomorphism. Differential topology is what Poincaré understood as topology or “analysis situs”.
2
votes
1
answer
190
views
Uniform smoothness of locally-flat loops
Let M be a smooth Riemannian manifold. Let $f:S^1\to M$ be a locally-flat injective loop. Must there exist such $\varepsilon>0$ that if we connect points $f(0),f(\varepsilon), f(2\varepsilon)... , f([ …
0
votes
degenerating immersion
The answer is no. Two 2-dim smooth immersed in $\mathbb R^3$ objects generically intersect by line, so if intersection is a point then it can be eliminated. But it is clear that near $z^2$ there are n …
0
votes
2
answers
353
views
Realisability cohomological class as product or as immersed sphere
Let's consider closed simply connected manifold $M^n$ and a $a\in H^k(M)$ and $a*\in H^{n-k}(M)$ is the dual to $a$.
Is it true that dual to $a$ is realisable as a immersed sphere or $ a*=bc $ for s …
6
votes
Accepted
Pairing used in Lefschetz duality
Yes, your formula is right. For the intuitive understanding just compute it for 1- and 2- dimensional half-spaces.
See Bott & Tu, Differential forms in Algebraic topology, $\S 5$, Poincaré duality.
…
3
votes
2
answers
299
views
Discriminant locus in knot space
Consider the space $K$ of all immersions of $S^1$ into $\mathbb R^3$.
The set of knots with self-intersection is a discriminant in $K$ and divide it into "chambers".
Let $f$ be a knot with $n$ double …
2
votes
1
answer
425
views
Stable singularities of smooth map $\mathbb R^3\to \mathbb R^4$
Does anybody know any classification of stable singularities of smooth map $f:\mathbb R^3\to \mathbb R^4$?
It is clear that there are singularities which look like intersection of 2 (or 3 or 4) hyper …
1
vote
Thom polynomial for contact algebraic structures
there is an article of Quo-Shin Chi "The dimension of the moduli space of superminimal surfaces of a fixed degree and conformal structure in the 4-sphere" where the dimension of contact curves moduli …
5
votes
3
answers
595
views
Thom polynomial for contact algebraic structures
Let's consider a algebraic contact structure $P$ on $\mathbb CP^3$
and a algebraic curve $C$ degree $d$ and genus $g$. Let's assume
that contact structure has degree $p$ (see
Polynomial contact struct …
10
votes
2
answers
891
views
Sum of two tangent bundles of $S^{2n}$
I was wondering if the sum $TS^{2n}\oplus TS^{2n}$ is a trivial bundle?
The same is true for spheres of odd dimension (one can find a nowhere zero section of the second bundle, add it to the first, th …
3
votes
1
answer
435
views
First cohomology of the space of long knots in ℝ⁴
Let's consider the space of long knots in $\mathbb R^n$, $n>3$. I know that there are many results (Vassiliev, Turchin, Sinha, Kontsevich) about different expressions of cohomology of this space. I th …
1
vote
Accepted
What is the simplest way to show that a section of a vector bundle is transverse to the zero...
It sounds like a multijet transversality theorem (see for example M. Golubitsky, V. Guillemin, Stable mappings and their singularities) in context of algebraic geometry. So, the answer is true --- a p …
7
votes
4
answers
968
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I was wondering if the set of singular loops is a (somewhere) submanifold of loop space?
The set of all smooth maps $S^1\to M^n$ ($M$ is a smooth manifold) is a generalized manifold(see http://ncatlab.org/nlab/show/smooth+loop+space).
I was wondering if the set of singular loops (maps wi …
5
votes
3
answers
2k
views
Minimal genus, adjunction inequality
Let's consider closed simply-connected 4-manifold $M$ and some $a\in H^2(M)$. It is very natural question to estimate minimal $g$ that $a$ can be presented as embedded surface of genus $g$.
As I know …