Questions tagged [differential-forms]
For questions about differential forms, a class of objects in differential geometry and multivariable calculus that can be integrated.
3,886 questions
-1 votes
0 answers
68 views
Contracting Metric Tensor and $df$ [closed]
In a previous post, I used an unusual method to derive the Gradient Theorem (i.e. the FTC for Line Integrals), and I simply reduced to the case of $\mathcal{M}=\gamma\subset\mathbb{R}^n$ to take ...
0 votes
1 answer
65 views
Where does this partition-of-unity argument not work in general?
I'm trying to solve problem 15-1 from Lee's Introduction to Smooth Manifolds, 2nd ed which states Suppose $M$ is a smooth manifold that is the union of two orientable open submanifolds with connected ...
2 votes
0 answers
42 views
Splitting of the Chiral de Rham differential for affine space
I am currently reading through Malikov, Schechtman and Vaintrob's paper Chiral de Rham Complex. In the proof of Theorem 2.4, i.e. that the chiral de Rham complex extends the usual de Rham complex for ...
3 votes
1 answer
110 views
Why isn't $\mathbb{RP}^n$ always orientable?
If $G$ is a Lie group and $H$ is a closed subgroup, the homogeneous space $G/H$ admits a $G$-invariant volume form if and only if ${\Delta_G}_{|H} = \Delta_H$ (where $\Delta_G$ and $\Delta_H$ are the ...
0 votes
0 answers
30 views
Question if a lemma from Miranda is classical u-sub
In Miranda’s Algebraic Curves & Riemann surfaces, in chapter IV. Integration on manifolds, Lemma 3.9(f) reads: If $F:X\to Y$ is a holomorphic map between Riemann surfaces, then the operation (push ...
2 votes
1 answer
177 views
Problem out of Miranda on Zero mean theorem
Let $X$ be a compact Riemann surface and suppose the zero mean theorem holds: Zero mean Theorem (p.318 Miranda):If $X$ is an algebraic curve and $\eta$ is a $C^\infty(X)$ $2-$form on it, then there ...
1 vote
0 answers
135 views
Miranda X.$2$.F.
Let $X$ be a compact Riemann surface. Let Bar: $\Omega^1(X)\to H^{(0,1)}_{\bar{\partial}}(X)$ by sending $\omega$ to the equivalence class of $\bar{\omega}$ is $\Bbb{C}-$linear, and $1-1$. Attempt: So ...
1 vote
0 answers
133 views
IV.I.$1$ out of Miranda Algebraic curves & Riemann Surfaces.
Let $L$ be a lattice in $\Bbb{C}$, and let $\pi$ be the natural protection. Show that $dz,d\bar{z}$ are well-defined holomorphic $1-$forms on $X=\Bbb{C}/L$. Attempt: I used charts because 2 are enough ...
0 votes
0 answers
54 views
Different (but equivalent) expression of a pullback
Consider the map $\varphi: M \to N$, $x^i$ a coordinate system on $M$ and $x'^i$ a coordinate system on $N$. $\alpha$ is a form. I was given the "fact" that $$(\varphi^*\alpha)_i(p) =\frac{\...
0 votes
0 answers
50 views
On scattering theory of Riemann Surfaces
In this 2025 paper on Scattering theory Scattering theory on Riemann Surfaces, I have some technical questions when tying it together with what I have learned in my courses. Let $R$ be a compact ...
2 votes
1 answer
147 views
On notational conventions between Bott & Tu Vs. Lee for differential forms
Since I have been introduced to differential forms, I have seen (naively speaking) when you apply the exterior derivative, you "wedge" together one additional $d$ of the variable in question ...
1 vote
1 answer
50 views
Exact iff your integral over $n$ sphere is zero.
Show $\eta\in\Omega^n(\Bbb{S}^n)$ is exact iff $\int_{\Bbb{S}^n}\eta=0$. Attempt: ($\Rightarrow)$ If $\eta$ is exact, there exists some $(n-1)-$form $\omega$ such that $\eta=d\omega$ then by Stokes', $...
0 votes
0 answers
128 views
Is there any sign mistake in computing the divergence in general coordinates?
$\newcommand{\pd}{\partial}$ $\newcommand{\wdw}{\wedge \cdots \wedge}$ $\newcommand{\cdc}{, \cdots ,}$ I'm trying to compute the divergence in general coordinates for the case of pseudo Riemannian ...
2 votes
0 answers
56 views
Possible typo in Wikipedia’s definition of isotropic and coisotropic submanifolds on the ‘Symplectic manifold’ page
I was reading the Wikipedia page on symplectic manifolds, and I think there might be a notational inconsistency in the section on Lagrangian and other submanifolds. The page defines, for a subspace $V ...
0 votes
1 answer
88 views
Real-Valued Differential Forms Acting on Vector-Valued Differential Forms
TL;DR Is it possible to act a real-valued 1-form on a vector-valued 1-form? If so, How? For context, in a previous post of mine, I proposed an admittedly unnecessary and lengthy approach to deriving/...