Local-time convergence conjecture for conditioned Galton–Watson trees

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Let ξ\xi, TξT_{\xi}, and ∣Tξ∣|T_{\xi}| be as in the conditioned Galton–Watson tree theorem, and write σ2=Var⁡ξ\sigma^2=\operatorname{Var}\xi. Let HnξH_n^{\xi} and CnξC_n^{\xi} denote respectively the height and contour functions of TξT_{\xi} conditioned to have n+1n+1 vertices, and let L(Hnξ;t,y)L(H_n^{\xi};t,y) and L(Cnξ;t,y)L(C_n^{\xi};t,y) be the corresponding continuous local-time functions defined by the formulas in the source. Let e\mathbf{e} be the normalized Brownian excursion and let η(2e/σ;t,y)\eta(2\mathbf{e}/\sigma;t,y) denote its local-time process. Local-time convergence conjecture. Along the subsequence for which P⁡(∣Tξ∣=n+1)>0\operatorname{\mathbb{P}}(|T_{\xi}|=n+1)>0, as n→∞n\to\infty, the joint local-time processes should converge in C([0,1]×R)C([0,1]\times\mathbb{R}) as follows:

(n−1/2L(Hnξ;nt,yn); t∈[0,1], y∈R)⟶d(η(2e/σ;t,y); t∈[0,1], y∈R),\Big(n^{-1/2}L(H_n^{\xi};nt,y\sqrt n);\ t\in[0,1],\ y\in\mathbb{R}\Big)\stackrel{\mathrm{d}}{\longrightarrow}\Big(\eta(2\mathbf{e}/\sigma;t,y);\ t\in[0,1],\ y\in\mathbb{R}\Big),

and

(n−1/2L(Cnξ;2nt,yn); t∈[0,1], y∈R)⟶d(2η(2e/σ;t,y); t∈[0,1], y∈R).\Big(n^{-1/2}L(C_n^{\xi};2nt,y\sqrt n);\ t\in[0,1],\ y\in\mathbb{R}\Big)\stackrel{\mathrm{d}}{\longrightarrow}\Big(2\eta(2\mathbf{e}/\sigma;t,y);\ t\in[0,1],\ y\in\mathbb{R}\Big).

The conjecture would provide a direct continuum analogue of the local-time convergence used in the paper's discrete approximation arguments, avoiding the intermediary study of maps. The source presents this as a hoped-for result rather than an established theorem, and does not provide a resolution.

References

Primary source

Grégory Miermont and Sanchayan Sen, “On breadth-first constructions of scaling limits of random graphs and random unicellular maps”, arXiv:1908.04403 (2021).

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