Result 211, Probability and statistical mechanics

The geometric phase diagram, diffusion, and spectra of random planar maps

Critical Fortuin–Kasteleyn planar maps converge to Liouville quantum gravity spheres for 0<q≤40\lt q\le4 and to the Brownian continuum random tree for q > 4, establishing the surface-to-tree geometric transition. For FK–Ising and spanning-tree-weighted maps, stationary random walks converge to Liouville Brownian motion on the limiting sphere. The FK–Ising spectral result also gives convergence of eigenvalues and heat traces, using the stated Brownian/LQG inputs.

Lean formalization Proof

The bigger picture

Why it matters

A random network drawn on a sphere can approach either a random surface or a branching tree as it grows. These manuscripts report where that change occurs and, in two specific models, how diffusion survives the limit.

What changes?

Fortuin-Kasteleyn (FK) maps are sphere-embedded graphs weighted by a statistical-mechanics model with parameter q. At criticality, the reported limits are unit-area Liouville quantum gravity spheres, random metric surfaces, for each fixed q above zero and at most four. For each fixed q above four, the limit is the Brownian continuum random tree. Distances are deterministically rescaled, by a constant times the inverse square root of the edge count above four. Convergence covers all positive integer edge counts.

What does that help mathematicians do?

For FK-Ising and maps weighted by their number of spanning trees, stationary walks reportedly converge to Liouville Brownian motion on unit-area spheres with parameters square root of three and square root of two, respectively. Walkers choose incident half-edges uniformly, retaining loops and multiple edges. At unit attempt rate, under the stated continuum normalization, time accelerates by exactly the edge count. Using companion geometric results, this identifies the continuum diffusion clock, not just the limiting shape.

Are there practical applications?

The immediate value is foundational: connecting random geometry to diffusion's decay rates. For FK-Ising specifically, the spectral manuscript reports joint convergence of geometry, all ordered eigenvalues with multiplicities, and heat traces, which summarize diffusion across modes. Heat-trace convergence is locally uniform at strictly positive times. These claims rely on companion conformal and metric-measure results and the stated Brownian and Liouville quantum gravity inputs.

This section was generated by GPT-6 Astra Medium. This explanation is based on the result summary and manuscript abstracts below. This context is separate from OpenAI's source text.

7 manuscripts

Random Walks on Critical FK–Ising Maps and Liouville Brownian Motion

October 5, 2026 16 pages

We prove that stationary random walks on critical spherical FK–Ising planar maps converge to Liouville Brownian motion on the ordinary unit-area 3\sqrt3-quantum sphere, using the geometric and electrical results of the spectral companion. The walk chooses uniformly among all incident half-edges, retaining loops and multiple edges. With the corner measure as the stationary law, the deterministic time acceleration is exactly the number of map edges. For any deterministic metric scale giving the metric-measure limit, convergence retains that same surface and any fixed finite number of conditionally independent walks with their time parameters.

Cite (BibTeX)
@misc{OAI:Random-Walks-on-Critical-FK-Ising-Maps-and-Liouville-Brownian-Motion-October-5-2026,
  author = {{OpenAI}},
  title = {{Random Walks on Critical FK--Ising Maps and Liouville Brownian Motion}},
  howpublished = {OpenAI Math Release preprint
                  \href{https://github.com/openai/math/blob/main/preprints/Random-Walks-on-Critical-FK-Ising-Maps-and-Liouville-Brownian-Motion-October-5-2026/fk-ising-walk-limit.pdf}{OAI:Random-Walks-on-Critical-FK-Ising-Maps-and-Liouville-Brownian-Motion-October-5-2026}},
  year = {2026}
}

Spectral convergence for critical FK–Ising planar maps

October 5, 2026 90 pages

Using the conformal and metric-measure companion results and the stated Brownian/Liouville quantum gravity inputs, we prove spectral convergence for critical spherical FK–Ising maps to Liouville Brownian motion on the ordinary unit-area 3\sqrt3-quantum sphere. The discrete walk has total attempt rate one, uses every map edge including loops and multiplicities, and has the corner measure as its stationary law. Accelerating time by the number of map edges gives joint convergence of the metric-measure space, all ordered eigenvalues with multiplicities and padding, and the heat trace locally uniformly at strictly positive times. The conductivity and clock constant are one in these conventions.

Cite (BibTeX)
@misc{OAI:Spectral-convergence-for-critical-FK-Ising-planar-maps-October-5-2026,
  author = {{OpenAI}},
  title = {{Spectral convergence for critical FK--Ising planar maps}},
  howpublished = {OpenAI Math Release preprint
                  \href{https://github.com/openai/math/blob/main/preprints/Spectral-convergence-for-critical-FK-Ising-planar-maps-October-5-2026/spectral-convergence-critical-fk-ising-planar-maps.pdf}{OAI:Spectral-convergence-for-critical-FK-Ising-planar-maps-October-5-2026}},
  year = {2026}
}

A Linear Clock for Random Walk on Tree-Weighted Planar Maps

October 5, 2026 59 pages

We prove that stationary random walk on a planar map sampled with weight equal to its number of spanning trees converges to Liouville Brownian motion on the unit-area 2\sqrt2-Liouville quantum sphere. The convergence retains the conditional path law jointly with the measured metric space. The walk chooses uniformly among all incident half-edges and starts from the stationary degree measure. For total attempt rate one and the continuum Dirichlet form with factor 1/2, the time acceleration is exactly the number of map edges. The result uses the companion contour and metric limits for this same ensemble.

Cite (BibTeX)
@misc{OAI:A-Linear-Clock-for-Random-Walk-on-Tree-Weighted-Planar-Maps-October-5-2026,
  author = {{OpenAI}},
  title = {{A Linear Clock for Random Walk on Tree-Weighted Planar Maps}},
  howpublished = {OpenAI Math Release preprint
                  \href{https://github.com/openai/math/blob/main/preprints/A-Linear-Clock-for-Random-Walk-on-Tree-Weighted-Planar-Maps-October-5-2026/linear-clock-random-walk-tree-weighted-planar-maps.pdf}{OAI:A-Linear-Clock-for-Random-Walk-on-Tree-Weighted-Planar-Maps-October-5-2026}},
  year = {2026}
}

Canonical conformal limits of subcritical FK planar maps

September 24, 2026 123 pages

For every fixed 0<q<40\lt q\lt 4, we prove joint convergence of spherical Fortuin–Kasteleyn planar maps in their flag-triangle uniformization to the corresponding unit-area Liouville quantum gravity sphere decorated by an independent conformal loop ensemble. The convergence includes the area measure, deterministically rescaled graph distances between all vertex pairs, and the full nested interface collection, with interfaces converging uniformly up to reparameterization.

Cite (BibTeX)
@misc{OAI:Canonical-conformal-limits-of-subcritical-FK-planar-maps-September-24-2026,
  author = {{OpenAI}},
  title = {{Canonical conformal limits of subcritical FK planar maps}},
  howpublished = {OpenAI Math Release preprint
                  \href{https://github.com/openai/math/blob/main/preprints/Canonical-conformal-limits-of-subcritical-FK-planar-maps-September-24-2026/main.pdf}{OAI:Canonical-conformal-limits-of-subcritical-FK-planar-maps-September-24-2026}},
  year = {2026}
}

The critical Liouville quantum sphere and geometric limits of FK maps at q=4

September 24, 2026 217 pages

We construct the field and area law of the unit-area critical Liouville quantum sphere as a limit of ordinary subcritical quantum spheres, and equip it with its critical intrinsic metric. We then prove that spherical Fortuin–Kasteleyn planar maps at q = 4, embedded by their equilateral flag uniformizations, converge jointly to this sphere decorated by an independent nested conformal loop ensemble CLE4. With deterministic distance normalization, the convergence includes the area measure, the full embedded distance function, and every macroscopic interface through all positive integer edge counts.

Cite (BibTeX)
@misc{OAI:The-critical-Liouville-quantum-sphere-and-geometric-limits-of-FK-maps-at-q-equals-4-September-24-2026,
  author = {{OpenAI}},
  title = {{The critical Liouville quantum sphere and geometric limits of FK maps at $q=4$}},
  howpublished = {OpenAI Math Release preprint
                  \href{https://github.com/openai/math/blob/main/preprints/The-critical-Liouville-quantum-sphere-and-geometric-limits-of-FK-maps-at-q-equals-4-September-24-2026/main.pdf}{OAI:The-critical-Liouville-quantum-sphere-and-geometric-limits-of-FK-maps-at-q-equals-4-September-24-2026}},
  year = {2026}
}

Metric-measure limits of subcritical FK and spanning-tree planar maps

September 24, 2026 232 pages

We resolve the finite spherical cases of Gwynne and Miller's graph-metric conjecture for critical Fortuin–Kasteleyn maps at each fixed q∈(0,4)q\in(0,4) and for uniform spanning-tree-decorated maps. After deterministic rescaling of graph distances, these maps, equipped with the vertex probability measure proportional to degree, converge in Gromov–Hausdorff–Prokhorov law to their ordinary unit-area Liouville quantum gravity spheres. Distances use every primal edge, and convergence holds through all positive integer edge counts.

Cite (BibTeX)
@misc{OAI:Metric-measure-limits-of-subcritical-FK-and-spanning-tree-planar-maps-September-24-2026,
  author = {{OpenAI}},
  title = {{Metric-measure limits of subcritical FK and spanning-tree planar maps}},
  howpublished = {OpenAI Math Release preprint
                  \href{https://github.com/openai/math/blob/main/preprints/Metric-measure-limits-of-subcritical-FK-and-spanning-tree-planar-maps-September-24-2026/main.pdf}{OAI:Metric-measure-limits-of-subcritical-FK-and-spanning-tree-planar-maps-September-24-2026}},
  year = {2026}
}

Brownian continuum random tree limits of finite Fortuin–Kasteleyn maps above four

September 24, 2026 25 pages

We prove the finite-volume continuum-random-tree prediction for critical Fortuin–Kasteleyn planar maps at every fixed q > 4. After rescaling graph distances by a constant times n−1/2, an n-edge map with normalized degree measure converges to the Brownian continuum random tree in the Gromov–Hausdorff–Prokhorov topology. The convergence holds through all positive integer sizes.

Cite (BibTeX)
@misc{OAI:Brownian-continuum-random-tree-limits-of-finite-Fortuin-Kasteleyn-maps-above-four-September-24-2026,
  author = {{OpenAI}},
  title = {{Brownian continuum random tree limits of finite Fortuin--Kasteleyn maps above four}},
  howpublished = {OpenAI Math Release preprint
                  \href{https://github.com/openai/math/blob/main/preprints/Brownian-continuum-random-tree-limits-of-finite-Fortuin-Kasteleyn-maps-above-four-September-24-2026/main.pdf}{OAI:Brownian-continuum-random-tree-limits-of-finite-Fortuin-Kasteleyn-maps-above-four-September-24-2026}},
  year = {2026}
}

Lean formalization

OpenAI's note on what the formalization covers, from lean/docs/211.md.

The geometric phase diagram, diffusion, and spectra of random planar maps

The following describes the scope of the Lean formalization related to the following accompanying paper(s):

Scope

For every fixed q>4q>4, the formalization proves the Brownian continuum-random-tree limit for critical finite Fortuin–Kasteleyn planar maps. After rescaling graph distances in an nn-edge map by a constant depending on qq times n−1/2n^{-1/2} and using normalized degree measure, the metric-measure space converges in distribution to the Brownian continuum random tree in the Gromov–Hausdorff–Prokhorov topology. The convergence holds through all positive integer sizes.

Comparator links

Result Comparator statement
Brownian continuum-random-tree limit for finite FK maps FKCRT.lean

Data from github.com/openai/math at commit adc7f12, committed October 6, 2026 at 21:58 UTC, last checked for changes about 9 hours ago. Titles, subjects, summaries, abstracts and Lean notes are OpenAI's; page counts are read from the PDFs. The map, related results, search, kinds of results and the named-problem index are Emergent Mind's, built with text embeddings and an LLM, and may contain errors.

An Emergent Mind Labs project. Emergent Mind is not affiliated with OpenAI. None of these results has been peer reviewed. Cite the manuscripts themselves, using the BibTeX on each result's page.