YangMills

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Name YangMills
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May
17
revised Dolbeault cohomology
edited tags
May
15
answered Dolbeault cohomology
May
8
comment Converse to Milnor’s theorem on manifolds with nonnegative Ricci curvature.
"cook one UP"...
Apr
27
comment H^d[U(1)^n,U(1)] of the Borel cohomology and Chern-Simons theory
@Idear: why do you keep capitalizing PHYSICS?
Apr
23
comment Energy functional
your Dirichlet energy is not correct!
Apr
19
comment Jet differentials and hyperbolicity: possible mistake in the literature?
I find it hard to believe that there is really a crucial mistake in the work of Demailly et al. It seems more likely that Sun's paper is not quite correct. I am particularly worried by the sentence "One can then compute... and see...".
Apr
14
awarded  Enlightened
Apr
14
awarded  Nice Answer
Mar
27
comment Another reference request about dualizing sheaves for nodal surfaces
This paper is also a classic: maths.ed.ac.uk/~aar/papers/durfee15.pdf
Mar
23
accepted infimum of the Calabi energy in a given Kahler class
Mar
22
revised infimum of the Calabi energy in a given Kahler class
added 704 characters in body
Mar
22
answered infimum of the Calabi energy in a given Kahler class
Mar
22
comment Sign convention in generalised Gauss-Bonnet
In other words, Deane's comment was exactly what you needed!!
Mar
21
comment Subadditivity of Kodaira dimension
If $X$ is just a compact complex manifold (not Kähler), then the statement is false. There is an example in the book of K. Ueno, "Classification theory of algebraic varieties and compact complex spaces", see the reference on page 1 of this paper arxiv.org/abs/1204.3165. I am not aware of any Kähler counterexample.
Mar
18
accepted Mukai-Umemura 3-fold and Kaehler-Einstein metrics
Mar
15
comment Alexandrov space where a Yau’s inequality that holds on Riemannian manifold fails
Also, how can you say that you know that the inequality does not hold on Alexandrov spaces when you have no such example? Maybe the inequality DOES hold on Alexandrov spaces!
Mar
15
comment Alexandrov space where a Yau’s inequality that holds on Riemannian manifold fails
duplicate of mathoverflow.net/questions/119592/…
Mar
1
comment Must a hyperbolic cone over Riemannian manifold be manifold?
Since you raised this question, can you please tell us why it must be a manifold?
Feb
22
awarded  Yearling
Feb
12
revised Are the Chern numbers of a hyperbolic-type compact complex manifold bounded in terms of the Euler number?
edited tags
Feb
12
comment Are the Chern numbers of a hyperbolic-type compact complex manifold bounded in terms of the Euler number?
Proposition 3.13 in this paper of Catanese-Schneider dx.doi.org/10.1007/BF01444736 gives universal bounds for the Chern numbers (assuming $K_X$ ample like you want) in terms of $(−1)^n c^n_1=K^n_X$. Does this help? When $n=3$, you also have the Yau inequality which bounds −$c^3_1\leq(8/3)(−c_1)c_2$, but then?
Feb
11
comment Are the Chern numbers of a hyperbolic-type compact complex manifold bounded in terms of the Euler number?
In this related question mathoverflow.net/questions/26586/… Dmitri points out that the answer is definitely NO if you drop the assumption of negative first Chern class.
Feb
5
comment Birational Automorphisms and infinite divisibility
Lieberman's theorem was also proved independently and simultaneously by A. Fujiki here link.springer.com/article/10.1007%2FBF01403162
Feb
4
revised First eigenvalue of $\Delta$ on Kaehler manifold with $Ricci\ge k$.
added 63 characters in body
Feb
4
revised First eigenvalue of $\Delta$ on Kaehler manifold with $Ricci\ge k$.
added 288 characters in body
Feb
1
accepted First eigenvalue of $\Delta$ on Kaehler manifold with $Ricci\ge k$.
Feb
1
answered First eigenvalue of $\Delta$ on Kaehler manifold with $Ricci\ge k$.
Jan
31
accepted What is the Weitzenböck formula for the $\bar\partial$-Laplacian
Jan
31
comment What is the Weitzenböck formula for the $\bar\partial$-Laplacian
I meant to write "complex gradient of $f$", but I think it's clearer now.
Jan
31
revised What is the Weitzenböck formula for the $\bar\partial$-Laplacian
added 13 characters in body
Jan
31
comment What is the Weitzenböck formula for the $\bar\partial$-Laplacian
$\partial f$ is the $(1,0)$ part of the differential $1$-form $df$. I will correct my wrong wording now, sorry.
Jan
30
answered What is the Weitzenböck formula for the $\bar\partial$-Laplacian
Jan
26
revised Why is the Bochner formula on an Alexandrov space worse than on a Riemannian manifold?
edited title
Jan
26
comment Deformations of Kähler manifolds where Hodge decomposition fails?
The paper of Popovici contained a mistake, so this theorem remains a conjecture. See here link.springer.com/article/10.1007/…
Jan
26
comment Mirror symmetry for hyperkahler manifold
I recommend you read section 7 of this paper of Gross arxiv.org/pdf/math/9809072.pdf, section 1 of Gross-Wilson arxiv.org/pdf/math/0008018v3.pdf, and this paper of Dolgachev arxiv.org/pdf/alg-geom/9502005v2.pdf
Jan
24
comment Moishezon manifolds with vanishing first Chern class
Thanks a lot, this is very interesting!
Jan
24
comment Digital Copy of Kato’s Paper
see also here (for bad news): mathoverflow.net/questions/96257/…
Jan
22
comment Can you get an Enrique surface from quotient of Abelian surface?
The answer is yes. For example, see Section 4 of this paper: arxiv.org/pdf/0909.5358.pdf
Jan
19
comment What are the general techniques for proving a variety is not toric?
It is definitely very easy to show that the automorphism group of the blowup of $\mathbb{P}^2$ in $s>3$ general points is discrete, since its Lie algebra is the space of holomorphic vector fields; on $\mathbb{P}^2$ this space has dimension $3$, and every time you blow up a point the dimension drops by one.
Jan
16
comment Functorial properties of blow-up
what is a diffeomorphism of singular varieties?
Jan
16
comment Useless math that became useful
Conic sections were apparently used by the Greeks (possibly Archimedes) in real life: en.wikipedia.org/wiki/Parabolic_reflector
Jan
12
comment Uniqueness of Kähler form with same volume
Keep in mind that in general noncompact Kahler manifolds two Kahler metric can have the same volume form without being equal (or isometric), for example the Taub-NUT metric on $\mathbb{C}^2$ and the standard flat metric have the same volume form.
Jan
10
comment The symmetric group and the field with one element
@Z254R: those two citations do not exist! I admit that I really don't get what you meant...
Jan
8
awarded  Nice Answer
Jan
5
comment New grand projects in contemporary math
just a minor comment about 3: Donaldson's article was actually written in 1996, and although it is supposed to be a reworking of his 1986 Fields Medallist lecture, the material on constant scalar curvature Kahler metrics (including the conjectures) is from 1996, which is roughly when Donaldson started thinking about those matters.
Dec
28
comment elliptic regularity on manifolds
Your assumptions imply that the function $u$ is in the Sobolev space $W^{2m,p}(M),$ and its $W^{2m,p}$ norm can be bounded in terms of its $L^q$ norm and the $L^p$ norm of $f$ (with a constant that depends on the geometry of $(M,g)$, on its dimension, on $p,q,m$). The proof of these facts is a simple application of the local results, using a partition of unity (as Paul Siegel says), and is something that you should really work out by yourself in detail at least once.
Dec
25
comment Compact Complex n-folds with Betti numbers $b_1=b_2=b_n=0$ for $n >3$
oops, I guess I read the OP's condition as $b_1=b_2=b_3=...=b_n=0$, which is apparently not what was asked!
Dec
25
comment Compact Complex n-folds with Betti numbers $b_1=b_2=b_n=0$ for $n >3$
yes, but it won't satisfy the OP's condition on the Betti numbers!
Dec
24
comment Why the sectional curvatures assume maximum on holomorphic planes for positively curved Kaehler manifold?
the proof that you want is on pages 154-155 there (even if you can't read French, I think you'll have no problem following the proof). Note that some inequalities on page 155 are wrong, and are corrected in the erratum (linked above).
Dec
22
awarded  Good Question