Skip to main content
Search type Search syntax
Tags [tag]
Exact "words here"
Author user:1234
user:me (yours)
Score score:3 (3+)
score:0 (none)
Answers answers:3 (3+)
answers:0 (none)
isaccepted:yes
hasaccepted:no
inquestion:1234
Views views:250
Code code:"if (foo != bar)"
Sections title:apples
body:"apples oranges"
URL url:"*.example.com"
Saves in:saves
Status closed:yes
duplicate:no
migrated:no
wiki:no
Types is:question
is:answer
Exclude -[tag]
-apples
For more details on advanced search visit our help page
Results tagged with
Search options not deleted user 24309

Dynamics of flows and maps (continuous and discrete time), including infinite-dimensional dynamics, Hamiltonian dynamics, ergodic theory.

13 votes

Homeomorphism of the circle with rational rotation number

The answer is "yes". Consider $\mathbb S^1$ as the quotient $\mathbb R/\mathbb Z$. Your homeomorphism $f$ lifts to a homeomorphism $\phi : \mathbb R \to \mathbb R$ such that $\phi(x+1)=\phi(x)+1$. For …
Daniele Tampieri's user avatar
5 votes

Are real-analytic functions in $\mathbb{R}^2$ holomorphic after suitable change of coordinates?

To see why the second question cannot have a simple answer, it is sufficient to look at the local context near a fixed-point of a tangent-to-identity mapping, as Alexandre Eremenko suggests. By "a sim …
Loïc Teyssier's user avatar
8 votes
1 answer
864 views

"Explicit" examples of Irrational numbers very well approximated by rational numbers

This question relates to this one and that one. Some background In the setting of discrete holomorphic dynamics (say, Julia sets) an irrational $\lambda$ is said to be well approximated by rational nu …
2 votes
Accepted

Analyticity of central stable manifolds

Quick answer to the first question: no, there is no reason why it should be analytic. Take e.g. the parametric vector field (written as a Lie derivative)$$X(x,y):=-x^3\partial_x+(y+\alpha x)\partial_y …
Loïc Teyssier's user avatar
5 votes
1 answer
219 views

Orbits space of real-analytic planar foliations

Consider a foliation of $\mathbb{R}^2$, say coming from the trajectories of a vector field $X$. Its orbit space (the quotient of $\mathbb{R}^2$ by the relation "lying on the same trajectory") is seldo …
2 votes
Accepted

Can a holomorphic vector field have an attractor homoclinic loop?

The answer is 'no' for much the same reason that the OP indicates: the existence of a homoclinic or heteroclinic connection implies that neighboring trajectories are periodic. First, one needs to have …
Loïc Teyssier's user avatar
2 votes

A Leibniz-like formula for $(f(x) \frac{d}{dx})^n f(x)$?

While not pretending to answer the OP, the following is too long to fit in a comment while it might contain elements of interest to the poster. If $f$ is a convergent object (smooth or analytic), then …
Loïc Teyssier's user avatar
5 votes
Accepted

Planar polynomial vector field for a harmonic pair of polynomials

First, this case is totally uninteresting regarding Hilbert XVI. Indeed, there are no limit cycles in such systems. The $\alpha / \omega$-limit of a trajectory is either a point or a non-isolated cycl …
Alexandre Eremenko's user avatar
3 votes

Polynomial vector field tangent to a given analytic simple closed curve

The answer is "no". In fact, it is still "no" for germs of curves : generically, a germ of an analytic curve $\gamma : (\mathbb R,0)\rightarrow (\mathbb R^2,0)$ is not tangent to any polynomial vector …
Loïc Teyssier's user avatar
2 votes
Accepted

A complete classification of linear foliations of $\mathbb{R}^n \setminus \{0\}$

I don't know offhand the answer of your first question, but I can answer the particular situation you describe afterwards : the holonomy is always trivial. First, notice that a compact leaf $L$ is e …
Loïc Teyssier's user avatar
2 votes
Accepted

The entire parametrization of leaves of singular holomorphic foliation of $\mathbb{C}P^2$

For your first question: $dy=y^2$ can be integrated by quadratures. The solutions are homographies. For your second question: no it is not true. By the uniformization theorem, the universal covering …
Loïc Teyssier's user avatar
2 votes
Accepted

Periodic orbits in the plane

The period of the compact, non-singular orbit $\gamma$ is given by $$T(\gamma)=\oint_\gamma \tau$$ where $\tau$ is any differential $1$-form such that $\tau(F)=1$, e.g. $\tau:=\frac{\mathrm{d}y_2}{\mu …
Loïc Teyssier's user avatar
0 votes
Accepted

Are codimension one foliations of $\mathbb{R}^{n}-\{0\}$ with compact leaves, stable at origin?

Yes. Let $\mathcal{F}$ be the foliation (of arbitrary dimension in $\{1,\ldots,n-1\}$), which I assume regular and transversely continuous. It is sufficient to consider the case of a ball $V$ of rad …
Loïc Teyssier's user avatar
5 votes
Accepted

Given $g(h(z))$ is convergent, what can be said about the convergence of $g(z)$ and $h(z)$?

If I understand correctly the setting (say $f$ is a germ at $0\in\mathbb C$ of a biholomorphic function), the answer is no in general, but yes generically. The diffeomorphismn $f$ can always be writte …
Community's user avatar
  • 1
1 vote
Accepted

Holomorphic vector field with infinite separatrix

No, a lot more vector fields have infinitely many separatrices. They are called «dicritical». For instance, you can change locally the analytic coordinates $(z_1,\ldots,z_n)$, the vector field will no …
Loïc Teyssier's user avatar

15 30 50 per page