probability-statistics / Ergodic theory on trees; Ising model, factors of IID

The Nam-Sly-Zhang conjecture: the free Ising state on the d-regular tree is a factor of IID up to the reconstruction threshold

Theorem 1.1: for every d≥3d\ge3 and β≥0\beta\ge0, μd,β\mu_{d,\beta} is a factor of IID if and only if tanh⁡β≤(d−1)−1/2\tanh\beta\le(d-1)^{-1/2}; the new part is the positive implication including equality, and the factor can be chosen to commute with every automorphism on every input. The converse is Sly's, as given by Lyons, with the Backhausz-Szegedy-Virag bound. The construction inverts the innovations of the Nam-Sly-Zhang stochastic-localization observation process. It does not treat antiferromagnetic or nonzero-field states, other Gibbs measures, or finitary factors.

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probability-statisticsSep 26, 2026Significance 16/100Registry: lean checked

The Nam-Sly-Zhang conjecture: the free Ising state on the d-regular tree is a factor of IID up to the reconstruction threshold

Prior state unknown→proved

Theorem 1.1: for every d≥3d\ge3 and β≥0\beta\ge0, μd,β\mu_{d,\beta} is a factor of IID if and only if tanh⁡β≤(d−1)−1/2\tanh\beta\le(d-1)^{-1/2}; the new part is the positive implication including equality, and the factor can be chosen to commute with every automorphism on every input. The converse is Sly's, as given by Lyons, with the Backhausz-Szegedy-Virag bound. The construction inverts the innovations of the Nam-Sly-Zhang stochas…

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Theorem 1.1: for every d≥3d\ge3 and β≥0\beta\ge0, μd,β\mu_{d,\beta} is a factor of IID if and only if tanh⁡β≤(d−1)−1/2\tanh\beta\le(d-1)^{-1/2}; the new part is the positive implication including equality, and the factor can be chosen to commute with every automorphism on every input. The converse is Sly's, as given by Lyons, with the Backhausz-Szegedy-Virag bound. The construction inverts the innovations of the Nam-Sly-Zhang stochastic-localization observation process. It does not treat antiferromagnetic or nonzero-field states, other Gibbs measures, or finitary factors.

Theorem 1.1: for every d≥3d\ge3 and β≥0\beta\ge0, μd,β\mu_{d,\beta} is a factor of IID if and only if tanh⁡β≤(d−1)−1/2\tanh\beta\le(d-1)^{-1/2}; the new part is the positive implication including equality, and the factor can be chosen to commute with every automorphism on every input. The converse is Sly's, as given by Lyons, with the Backhausz-Szegedy-Virag bound. The construction inverts the innovations of the Nam-Sly-Zhang stochastic-localization observation process. It does not treat antiferromagnetic or nonzero-field states, other Gibbs measures, or finitary factors.

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The Nam-Sly-Zhang conjecture: the free Ising state on the d-regular tree is a factor of IID up to the reconstruction threshold — Mathematical Frontier Network