2
votes
1answer
87 views
about smoothing pseudodifferential operators
Hi,
I have a question which involves pdo.
Let us consider a pseudodifferential operator $A:S(\mathbb{R}^d)\rightarrow S(\mathbb{R}^d) $ whose symbol $a(x,\xi)$ lives in the $S_{0, …
10
votes
5answers
314 views
What are the invariant Pseudo-differential operators on a Lie group?
It is well-known that (left) $G$-invariant differential operators on a Lie group $G$, has an algebraic description, i.e. universal enveloping algebra of the Lie algebra of the grou …
8
votes
1answer
213 views
Applications of pseudodifferential operators to PDE
I am planning to build a PDE course centred around pseudodifferential operators. I know some important applications of pseudodifferential operators to PDEs, but I don't know enough …
1
vote
1answer
68 views
Analogue of the integral Fourier operator with angle in some cone
Let $\Phi(x,y,\theta)$ be a phase function defined on $X \times X \times (\mathbb R^n-0)$ where $X$ is some domain in $\mathbb R^n$, let $A(x,y,\theta)$ be an amplitude function. A …
5
votes
1answer
146 views
Trace formula for PSDOs
In Getzler's famous paper "Pseudodifferential Operators on Supermanifolds and the Atiyah-Singer Index Theorem", he states that for a (trace-class) pseudo-differential operator $P$ …
3
votes
2answers
185 views
When is a Pseudo-differential operator trace class or in Dixmier ideal?
Let's denote the set of all Pseudo-differential operators with symbol of “order” $d$ by $\Psi_d(M)$ and Sobolev space on $M$ by $H_s(M)$. It is known that
If $P\in\Psi_d(M)$ Th …
15
votes
4answers
1k views
Why is symplectic geometry so important in modern PDE ?
First, we recall that symplectic manifold is a smooth manifold, $M$, equipped with a closed nondegenerate differential 2-form, $\omega$, called the symplectic form. The study of sy …
4
votes
1answer
513 views
Pseudo-differential operators which are independent of lower order perturbations
In the area of pseudo-differential operators, we know that for elliptic type or real principal type operators reductions are independent of lower order terms. For example, if $P$ i …
11
votes
6answers
1k views
Square roots of the Laplace operator
In several places in the literature (e.g. this paper of Caffarelli and Silvestre), I've seen an integral formula for fractional Laplacians. I'd like to understand it. In this que …
8
votes
2answers
503 views
what’s the motivation of Weyl calculus ?
In the pseudo-differential operator theory, we can define a pseudo-differential operator by $$a(x,D)u=(2\pi)^{-n}\int{a(x,\xi)e^{i\langle x-y,\xi \rangle}u(y)dyd\xi}$$ with $a(x,\ …
19
votes
7answers
2k views
Motivation for and history of pseudo-differential operators
Suppose you start from partial differential equations and functional analysis (on $\mathbb R^n$ and on real manifolds, which prominent example problems lead you to work with Pseudo …
2
votes
0answers
71 views
Exponential decay for the gradient of a solution
Dear all,
I would like to prove the exponential decay of the derivatives of a solution to the following equation in $\mathbb{R}^N$:
$$
\sqrt{-\Delta+m^2} u +u= f(u),
$$
where I can …
7
votes
1answer
313 views
Why take ‘complex powers’ of pseudo-differential operators?
Given a pseudo-differential operator $P$ of order zero, Seeley showed that the holomorphic family of operators $\lbrace P^{z} : z\in \mathbb{C} \rbrace$ of all complex powers is c …
2
votes
2answers
97 views
a question about first-order hyperbolic equations
Performing certain manipulations on pseudo-differential equations I have come across the following first order equation:
$$
D_{t}u-\lambda(t,x,D_{t},D_{x})u=0, \ \ (*)
$$
where $\l …
0
votes
1answer
141 views
On the generalization of the Mittag-Leffler function and fractional derivative
The Mittag-Leffler function $E_{\alpha}(x)$ has an important property:
$$
\frac{\partial^{\alpha}}{\partial x^{\alpha}} E_{\alpha}(x^{\alpha}) = E_{\alpha}(x^{\alpha}).
$$
I tr …

