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Complex, contact, Riemannian, pseudo-Riemannian and Finsler geometry, relativity, gauge theory, global analysis.

0 votes
1 answer
317 views

Is the kernel of a map between finite dimensional vector bundles still of finite type?

I'm not sure whether the level of this question is suitable for Mathoverflow. Let $M$ be a smooth manifold, $E$ and $F$ are finite dimensional (smooth) vector bundles on $M$. Let $\phi: E\rightarrow …
Zhaoting Wei's user avatar
  • 9,019
6 votes
Accepted

Why is the Tangent Groupoid useful in non-commutative geometry?

The tangent groupoid can be used in constructing the index map and proving the Atiyah-Singer index theorem. This may illustrate its importance. Higson and Roe will write a book on it.
Zhaoting Wei's user avatar
  • 9,019
1 vote
0 answers
51 views

Do we have a $4$-term decomposition of $\bar{\partial}_M$ for a holomorphic fiber bundle $M\...

First let us consider a Riemannian fiber bundle, i.e a fiber bundle $\pi: M\to B$ of oriented Riemannian manifolds. We denote by $T(M/B)$ the bundle of vertical tangent vectors and assume that the bun …
Zhaoting Wei's user avatar
  • 9,019
5 votes
0 answers
82 views

Does $\Lambda^2_{+}$ generate a differential ideal for a self-dual $4$-manifold?

Let $(X, g)$ be a smooth, oriented, Riemannian 4-diemnsional manifold. Let $\Lambda^2$ denote the bundle of 2-forms on $X$. Then the Hodge-star operator decomposes $\Lambda^2$ into the space of self-d …
Zhaoting Wei's user avatar
  • 9,019
1 vote
1 answer
164 views

Find an action of $\mathbb{Z}/2$ on $\mathbb{C}P^1$ which is compatible with the fraction l...

There is a natural fraction linear transform of $SL(2,\mathbb{R})$ on $\mathbb{C}P^1$ given by: $$ \begin{pmatrix} a & b \\ c & d \end{pmatrix} \cdot[z,w]=[az+bw,cz+dw]. $$ Let $\mathbb{Z}/2=\{ 1,s \ …
Zhaoting Wei's user avatar
  • 9,019
1 vote
0 answers
289 views

Can we classify two dimensional complex vector bundles over $\mathbb{R}P^2$?

I know it is easy to classify line bundles over $\mathbb{R}P^2$. But do we have a classification of two dimensional complex vector bundles over $\mathbb{R}P^2$?
Zhaoting Wei's user avatar
  • 9,019
4 votes
0 answers
158 views

Do we have classical Riemann-Hilbert correspondence for infinite dimensional flat vector bun...

Let $E$ be an $n$-dimensional vector bundle on a manifold $M$ and $\nabla: \Gamma(E)\to \Omega^1(M,E)$ be a flat connection on $E$. Classical Riemann-Hilbert correspondence tells us that ker$\nabla$ i …
Zhaoting Wei's user avatar
  • 9,019
4 votes
0 answers
225 views

Will the transgression formula for superconnections give back the transgression formula of c...

Let $E$ be a vector bundle on a smooth manifold $X$ and $\nabla$ be a connection on $E$, by Chern-Weil theory, the Chern character of $(E,\nabla)$ could be construct as $$ ch(E,\nabla):=tr(\exp(-\nab …
Zhaoting Wei's user avatar
  • 9,019
5 votes
1 answer
250 views

Does a compact Lie group action on a family of compact manifolds have diffeomorphic fixed po...

Let $\pi: M\to B$ be a fiber bundle of smooth manifolds with $B$ connected and each fiber of $\pi$ is a compact manifold. Let $G$ be a compact Lie group acting smoothly on $M$ such that $\pi(g\cdot m) …
Zhaoting Wei's user avatar
  • 9,019
3 votes
1 answer
99 views

Do we have an equivariant version of integrability theorem of flat connections?

I am reading Donaldson and Kronheimer's book The Geometry of Four-Manifolds. In page 48, I found Theorem 2.2.1: Let $H$ be the hypercube $H=\{\mathbf{x}\in \mathbb{R}^d|~|x_i|<1\}$. If $E$ is a bundle …
Zhaoting Wei's user avatar
  • 9,019
3 votes
1 answer
168 views

Do we have $d(P_{+}(\omega\wedge \theta))=d_{+}\omega\wedge \theta-\omega\wedge d_{+}\theta$...

Let $(X, g)$ be a smooth, oriented, Riemannian 4-diemnsional manifold. Let $\Lambda^2$ denote the bundle of 2-forms on $X$. Then the Hodge-star operator decomposes $\Lambda^2$ into the space of self-d …
Zhaoting Wei's user avatar
  • 9,019
7 votes
3 answers
1k views

Is there a "by hand" proof on the symmetry of the Atiyah class of $TX$?

Let X be a complex manifold and $TX$ its tangent bundle. The Atiyah class $\alpha(E)\in \text{Ext}^1(E\otimes TX, E)$ for a vector bundle $E$ is defined to be the obstruction of the global existence o …
Zhaoting Wei's user avatar
  • 9,019
8 votes

Does there exist a GRR-like generalization of the AS Index Theorem?

I'm sorry for the self-citation. But your question is largely answered in the monograph Coherent Sheaves, Superconnections, and Riemann-Roch-Grothendieck, or the arxiv version, joint work of Jean-Mich …
Zhaoting Wei's user avatar
  • 9,019
10 votes
0 answers
737 views

What is Quillen's contribution to index theorem?

In the book "Heat Kernels and Dirac Operators" by Berline, Getzler and Vergne it is said that "Our book is based on a simple principle, which we learned from D. Quillen: Dirac operators are a quantiza …
Zhaoting Wei's user avatar
  • 9,019
4 votes
2 answers
814 views

The relation between the heat kernel on the principal bundle and the heat kernel on the base...

This question is mainly about Section 5.2 of the book "Heat Kernels and Dirac Operators" by Berline, Getzler and Vergne. Let $M$ be a compact Riemannian manifold without boundary and $P\rightarrow M$ …
Zhaoting Wei's user avatar
  • 9,019

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