The Tutte Embedding of the Poisson–Voronoi Tessellation of the Brownian Disk Converges to √8/3 -Liouville Quantum Gravity
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jats:titleAbstract</jats:title> jats:pRecent works have shown that an instance of a Brownian surface (such as the Brownian map or Brownian disk) a.s. has a canonical conformal structure under which it is equivalent to a jats:inline-formulajats:alternativesjats:tex-math$$\sqrt{8/3}$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">mml:msqrtmml:mrowmml:mn8</mml:mn>mml:mo/</mml:mo>mml:mn3</mml:mn></mml:mrow></mml:msqrt></mml:math></jats:alternatives></jats:inline-formula>-Liouville quantum gravity (LQG) surface. In particular, Brownian motion on a Brownian surface is well-defined. The construction in these works is indirect, however, and leaves open a basic question: is Brownian motion on a Brownian surface the limit of simple random walk on increasingly fine discretizations of that surface, the way Brownian motion on jats:inline-formulajats:alternativesjats:tex-math$$\mathbb {R}^2$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">mml:msupmml:mrowmml:miR</mml:mi></mml:mrow>mml:mn2</mml:mn></mml:msup></mml:math></jats:alternatives></jats:inline-formula> is the jats:inline-formulajats:alternativesjats:tex-math$$\epsilon \rightarrow 0$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">mml:mrowmml:miϵ</mml:mi>mml:mo→</mml:mo>mml:mn0</mml:mn></mml:mrow></mml:math></jats:alternatives></jats:inline-formula> limit of simple random walk on jats:inline-formulajats:alternativesjats:tex-math$$\epsilon \mathbb {Z}^2$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">mml:mrowmml:miϵ</mml:mi>mml:msupmml:mrowmml:miZ</mml:mi></mml:mrow>mml:mn2</mml:mn></mml:msup></mml:mrow></mml:math></jats:alternatives></jats:inline-formula>? We answer this question affirmatively by showing that Brownian motion on a Brownian surface is (up to time change) the jats:inline-formulajats:alternativesjats:tex-math$$\lambda \rightarrow \infty $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">mml:mrowmml:miλ</mml:mi>mml:mo→</mml:mo>mml:mi∞</mml:mi></mml:mrow></mml:math></jats:alternatives></jats:inline-formula> limit of simple random walk on the Voronoi tessellation induced by a Poisson point process whose intensity is jats:inline-formulajats:alternativesjats:tex-math$$\lambda $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">mml:miλ</mml:mi></mml:math></jats:alternatives></jats:inline-formula> times the associated area measure. Among other things, this implies that as jats:inline-formulajats:alternativesjats:tex-math$$\lambda \rightarrow \infty $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">mml:mrowmml:miλ</mml:mi>mml:mo→</mml:mo>mml:mi∞</mml:mi></mml:mrow></mml:math></jats:alternatives></jats:inline-formula> the jats:italicTutte embedding</jats:italic> (a.k.a. jats:italicharmonic embedding</jats:italic>) of the discretized Brownian disk converges to the canonical conformal embedding of the continuum Brownian disk, which in turn corresponds to jats:inline-formulajats:alternativesjats:tex-math$$\sqrt{8/3}$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">mml:msqrtmml:mrowmml:mn8</mml:mn>mml:mo/</mml:mo>mml:mn3</mml:mn></mml:mrow></mml:msqrt></mml:math></jats:alternatives></jats:inline-formula>-LQG. Along the way, we obtain other independently interesting facts about conformal embeddings of Brownian surfaces, including information about the Euclidean shapes of embedded metric balls and Voronoi cells. For example, we derive moment estimates that imply, in a certain precise sense, that these shapes are unlikely to be very long and thin.</jats:p>
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1432-0916