Borel summation, Mellin Transforms, Parabolic iteration
#2
(09/03/2022, 03:02 AM)JmsNxn Wrote: So to begin, we'll get some concepts clear. A parabolic fixed point \(f(0) = 0\) and \(f'(0) = e^{2 \pi i m/q}\) for \(q,m \in \mathbb{Z}\). And the multiplier of this fixed point, as Milnor states it, or the \(\ell = \text{valit}\) as Bo, refers to it, is given in the expansion:
I think you mean "multiplicity", perhaps edit that in your original post - because it is called "multiplier" in the hyperbolic case for the first coefficient, right?
EDIT: After reading Milnor again: the multiplicity is valit+1, they are not the same. The multiplicity is the index of the first non-zero coefficient after the first coefficient. Valit is the multiplicity - 1. The number of petals is 2*valit.

(09/03/2022, 03:02 AM)JmsNxn Wrote: Here is where things start to get difficult. We have an abel function on half plane, which is really just the abel function of our function \(f\), but fixated in a petal, and near \(0\). We have to from here, restrict (we don't have to in the final result, but we do now). This function \(\alpha(w)\) satisfies the asymptotic expansion:

\[
\alpha(w) = w + A \log(w) + \sum_{k=0}^\infty b_k w^{-k}\\
\]

Where the coefficients \(b_k\) are of order \(O(c^kk!)\) for some random value \(c\) which is unimportant to us. This asymptotic only holds for \(|\arg(w)|  < \kappa\), for some value \(\kappa>0\)--dependent on the multiplicity of this fixed point (Milnor), or the valit, as Bo calls it.

But I would like to remark here that asymptotics is for all petals the same, only the branch(cut) of the logarithm is what needs to be adjusted from petal to petal.

(09/03/2022, 03:02 AM)JmsNxn Wrote: And so enters in our new change of variables \(u = 1/w\):
\[
\alpha(u) = \frac{1}{u} - A \log(u) + \sum_{k=0}^\infty b_k u^k\\
\]
Don't you need more terms \(\frac{1}{u^k}\) and also having coefficients, like:
\[ \alpha(u) = \left(\sum_{k=1}^{\ell} \frac{c_k}{u^k}\right) - A \log(u) + \sum_{k=0}^\infty b_k u^k \]

(09/03/2022, 03:02 AM)JmsNxn Wrote: \[
T_c(u) = \int_{c-i\infty}^{c+i\infty} \frac{H(s)}{\Gamma(1-s)} u^{-s}\,ds\\
\]

We get the perfect version of:

\[
T_c(u) = \sum_{k=1}^\infty \frac{b_k}{k!}u^k
\]

Where we can choose the index \(k=1\) by moving \(c\) to the right or left. For \(c = \delta - N\) we get:

\[
T_c(u) = \sum_{k=N}^\infty \frac{b_k}{k!}u^k
\]

Where, (I'm not sure if this converges, if it doesn't, it's irrelevant), if \(c = 1+\delta\) we have the borel sum of the Alpha function.

Therefore:

\[
\int_0^\infty e^{-t/u}T_{1+\delta}(t) \,dt = \alpha(u)\\
\]

But now, in addition to everything above, this will prove A GLOBAL SOLUTION OF OUR BOREL SUM METHODOLOGY!
Where do \(\delta\) and N come from?
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Messages In This Thread
RE: Borel summation, Mellin Transforms, Parabolic iteration - by bo198214 - 09/09/2022, 08:23 PM

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