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Given a positive Borel measure without atoms $\tau$ on the circle $\mathbb T =\mathbb R /\mathbb Z =[0,1)$ , in https://arxiv.org/abs/0912.3423 a homeomorphism $h:[0,1)\to [0,1)$ is defined as \begin{equation} h(t)=\tau ([0,t))/\tau ([0,1) )%\qquad \mbox{for}\;\; \theta\in [0,1) \label{h1} \end{equation} Specifically they take $\tau$ formally proportional to $ e^{\beta X(t)}dt$ where $\beta\geq 0$ and $X$ is the Gaussian Free Field on the circle i.e. the random field $X$ with covariance $\mathbb E\, X(t)X(t')=-\log |e^{2\pi it}-e^{2\pi it'}|$ (see within the link and https://arxiv.org/abs/0909.1003 for all the rigorous details).

Questions:

  • Is the map $\tau \mapsto h$ a homeomorphism between some space and the space of homeomorphisms of the circle?
  • Can we use this map to define a measure on the space of homeomorphisms of the circle?
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  • $\begingroup$ 1. What topologies are you taking on each space? 2. Assume it is, how would you use this to build a measure? $\endgroup$
    – Asaf
    Commented Sep 11, 2022 at 3:25
  • $\begingroup$ Anyhow, the construction is false (or at-least inaccurate), taking say the Bernoulli measure over the regular Cantor set, this construction doesn't yield a homeomorphism as it will not be injective (over any subset you ``deleted'' from the Cantor set). The construction must implicitly assume the given measure is ac with respect to Lebesgue and fully supported, this indeed yields a monotone function as $h(t)$. $\endgroup$
    – Asaf
    Commented Sep 12, 2022 at 3:49

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