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Search options not deleted user 36688
2 votes
0 answers
209 views

A particular case of of the higher dimensional Poincare Bendixson theorem

We consider the planar polynomial vector field $$(*) \;\;\;\begin{cases} \dot x= P(x,y) \newline \dot y =Q(x,y)\end{cases}$$ We replace the real variables $x,y$ with complex variables $x:=x_{1}+ …
Ali Taghavi's user avatar
1 vote
1 answer
156 views

The index of certain differential operator on tori

Assume that $J$ is an almost complex structure on torus $\mathbb{T}^2$. Let $X$ be a non vanishing vector field on the torus. Let $g$ be a Riemannian metric with corresponding $LC$ connection …
Ali Taghavi's user avatar
4 votes
1 answer
300 views

Fredholm subvector spaces of $B(\mathcal{H})$

Let $\mathcal{H}$ be a separable Hilbert space with orthonormal base $\{e_i\}\;\;i\in \mathbb{N}$. Definition: We say a subvector space $W\subset B(\mathcal{H})$ is a Fredholm subspace if the …
Ali Taghavi's user avatar
1 vote
0 answers
59 views

Ellipticity of certain differential operator associated to a pair of vector field via curvat...

What is a precise example of the following situation: A compact Riemanian manifold $M$ admits two vector field $X,Y$ such that the the operator $$Z\mapsto R(X,Y)Z$$ Would be an elliptic operator and …
Ali Taghavi's user avatar
0 votes
0 answers
62 views

A uniform upper bound for Fredholm index of Laplace quasi-operators on a compact paralleliza...

Assume that $M$ is a compact parallelizable manifold. Is there an upper bound for the absolute value of Fredholm index of all operators in the form $D=\sum_{i=1}^n \partial^2/\partial{X_i^2} …
Ali Taghavi's user avatar
1 vote
0 answers
308 views

A differential operator associated with a vector field on the torus

Assume that $X$ is a non vanishing vector field on the torus $\mathbb{T}^2$. We define two linear operators $T,S$ on the space of smooth functions on $\mathbb{T}^2$ as follows: $T(f)= …
Ali Taghavi's user avatar
2 votes
0 answers
90 views

A quantity associated to a compact Riemannian manifold with boundary(The pair of Laplacian)

Let $M$ be a Riemannian manifold with boundary $\partial M$. Are the following operators, Fredholm operators?Is there a geometric terminology and geometric interpretation for the fredholm index of the …
Ali Taghavi's user avatar
2 votes

Generalization of winding number to higher dimensions

In your question you mentioned the word "Fredholm index". So I would like to say that in the circle case there are two different interpretations of Fredholm index of certain lin …
Ali Taghavi's user avatar
11 votes
2 answers
1k views

Elliptic operators corresponds to non vanishing vector fields

Added, June 19, 2019: The main motivation of this post is to associate an index to differential operator associated to a dynamical system such that the index has an interesting dy …
Ali Taghavi's user avatar
2 votes
0 answers
108 views

Uniform upper bound for dim of kernel and codimension of range of certain familly of PDE

A polynomial vector field of degree $n$ on $S^{2}$ is the Poincare compactification of a $n$ degree polynomial vector field on $\mathbb{R}^{2}$.It is a real analytic vector field on $S^{2}$ which …
Ali Taghavi's user avatar
6 votes
1 answer
340 views

Fredholm theory of non elliptic operators

In this question we search for a big list of non elliptic operators whose Fredholm index is finite or whose Fredholm theory is extensively discussed. The main motovation is the conference linked in th …