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OP-01148 Open

Continuing stochastic Ricci flow through zero total area

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Let $(\Sigma, g)$ be a connected closed orientable smooth Riemannian surface with Euler characteristic $\chi(\Sigma)$. Fix $0 < \gamma < 2$, $\mu > 0$, distinct points $x_i \in \Sigma$ and real charges $\alpha_i < Q$, where $$Q = \frac2\gamma + \frac\gamma2, \qquad \bar\alpha = \sum_i \alpha_i, \qquad 0 < \bar\alpha - Q\chi(\Sigma) < \gamma.$$ Let $m$ be the finite Liouville area-measure law with these vertex insertions, as in Dubédat and Shen (Section 4.2): the push-forward of the field law $\nu_g^\alpha$ by the Gaussian multiplicative chaos map $X \mapsto M_\gamma(X) = {:}e^{\gamma X}{:}_g\,dV_g$. Let $\mathcal X = \mathcal M_+(\Sigma) \setminus \{0\}$, where $\mathcal M_+(\Sigma)$ is the space of finite nonnegative Borel measures on $\Sigma$ with the weak topology, and let $A$ be the $m$-symmetric stochastic Ricci flow of their Theorem 4.3: the diffusion of the closure of $$\mathcal E(F,G) = \gamma^2 \int_{\mathcal X} \sum_{i,j} (\partial_i q)(\partial_j r)\, a(f_i h_j)\, m(da)$$ on smooth cylinder functions $F(a) = q(a(f_0), \dots, a(f_k))$, $f_0 = 1$, and $G(a) = r(a(h_0), \dots, a(h_l))$, with smooth $f_i, h_j$ and compact support in $\mathcal X$ (total mass bounded away from zero), started from quasi-every state. In particular $A$ is killed when it reaches the zero measure. Dubédat and Shen showed that the total area $A_t(\Sigma)$ is a diffusion with generator $$\gamma^2 x\,\partial_{xx} + \bigl(\gamma(\bar\alpha - Q\chi(\Sigma)) - \mu\gamma^2 x\bigr)\partial_x,$$ which behaves at $0$ like a squared Bessel process of dimension $\delta = \frac2\gamma(\bar\alpha - Q\chi(\Sigma))$; the condition on $\bar\alpha$ says $0 < \delta < 2$, the range in which the total area hits zero and can be continued.

Problem. Does there exist a conservative continuous strong Markov process $\widetilde A$ on $\overline{\mathcal X} = \mathcal X \cup \{0\}$ whose part process on $\mathcal X$ agrees with $A$, up to the usual exceptional-set equivalence, and such that for every finite $T$ $$\int_0^T \mathbf 1_{\{\widetilde A_t(\Sigma) = 0\}}\,dt = 0 \quad \text{almost surely?}$$

Source: Dubédat and Shen (2022), Section 5, Question 6. Stated by AIM — Open Applied Problems for closed orientable surfaces, as a continuous strong Markov extension of the diffusion of their Theorem 4.3.

Imported from github.com/MColbrook/AIM.

Classification

Primary
PR — Probability
Secondary
DG, MP
Keywords
AIM Open Applied Problems, Dirichlet forms, Liouville quantum gravity, stochastic Ricci flow
Literature checked
Nov. 5, 2026 by clemens-admin

References

@article{dubedat2022,
  author        = {Dub{\'e}dat, Julien and Shen, Hao},
  title         = {Stochastic {R}icci flow on compact surfaces},
  journal       = {Int. Math. Res. Not. IMRN},
  volume        = {2022},
  number        = {16},
  year          = {2022},
  pages         = {12253--12301},
  doi           = {10.1093/imrn/rnab015},
  eprint        = {1904.10909},
  archivePrefix = {arXiv},
}
@misc{aim-continuing-stochastic-ricci-flow-through-zero-total-area,
  author       = {Brunton, Steve and Colbrook, Matthew J. and de Hoop, Maarten V. and Stepaniants, George and Townsend, Alex and Ward, Rachel},
  title        = {{Continuing stochastic Ricci flow through zero total area}},
  howpublished = {AIM --- Open Applied Problems, GitHub repository},
  year         = {2026},
  url          = {https://github.com/MColbrook/AIM/blob/4f5b1659355cb61d194da94ef14615214e1363a8/problems/1003-continuing-stochastic-ricci-flow-through-zero-total-area.md},
  note         = {Entry 1003 at commit 4f5b165, 2026-11-04},
}

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OP-01148, "Continuing stochastic Ricci flow through zero total area", clopen.solutions.