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Sharpness of the Kesten-Stigum reconstruction threshold for three-state symmetric and ferromagnetic four-state Potts channels on trees

Three-state theorem: for the symmetric channel with −1/2≤λ≤1-1/2\le\lambda\le1, on every bb-ary tree (b≥2b\ge2) and every observed Poisson(dd) tree with d>1d>1, reconstruction holds iff dλ2>1d\lambda^2>1, with non-reconstruction at equality for both signs (so the 3-coloring channel is non-reconstructible at branching four). Corollary: weak recovery in the symmetric three-community sparse block model is possible iff (a−b)2>3(a+2b)(a-b)^2>3(a+2b). Four-state theorem: for the ferromagnetic channel (0≤λ≤10\le\lambda\le1), non-reconstruction whenever dλ2≤1d\lambda^2\le1 on dd-ary and Poisson trees. Companion: an L3L^3-capacity criterion for four-state reconstruction on bounded-degree trees. Not shown: the antiferromagnetic four-state channel.

Exact FrontierDelta

Prior state unknown→proved

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Occurred: Sep 25, 2026

Delta type: SOURCE CLAIM

Assumptions: VibeMathed verification: unreviewed. Publication: announcement. AI contribution: ai-discovered. VibeMathed editorial classifications, scores, notes, relations, and dataset structure are CC BY 4.0. Source statements and linked content retain their own rights.

Canonical aliases: Sharpness of the Kesten-Stigum reconstruction threshold for three-state symmetric and ferromagnetic four-state Potts channels on trees · Kesten-Stigum sharpness for 3 and 4 states

Confidence: Not scored

Registry verification: unreviewed · announcement · candidate

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VibeMathed
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Unreleased internal OpenAI model
model · ai model contributor · OpenAI

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Lean Comparator challenge ThreeStateSupercritical (supercritical direction only)

lean artifact · pending

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This event attributed to Unreleased internal OpenAI model

Sharpness of the Kesten-Stigum reconstruction threshold for three-state symmetric and ferromagnetic four-state Potts channels on trees evidence for this event

Sharpness of the Kesten-Stigum reconstruction threshold for three-state symmetric and ferromagnetic four-state Potts channels on trees parent of this event

Lean Comparator challenge ThreeStateSupercritical (supercritical direction only) evidence for this event

VibeMathed record: Sharpness of the Kesten-Stigum reconstruction threshold for three-state symmetric and ferromagnetic four-state Potts channels on trees evidence for this event

Companion: The reconstruction threshold for the ferromagnetic four-state Potts model evidence for this event

Three-state theorem: for the symmetric channel with −1/2≤λ≤1-1/2\le\lambda\le1, on every bb-ary tree (b≥2b\ge2) and every observed Poisson(dd) tree with d>1d>1, reconstruction holds iff dλ2>1d\lambda^2>1, with non-reconstruction at equality for both signs (so the 3-coloring channel is non-reconstructible at branching four). Corollary: weak recovery in the symmetric three-community sparse block model is possible iff (a−b)2>3(a+2b)(a-b)^2>3(a+2b). Four-state theorem: for the ferromagnetic channel (0≤λ≤10\le\lambda\le1), non-reconstruction whenever dλ2≤1d\lambda^2\le1 on dd-ary and Poisson trees. Companion: an L3L^3-capacity criterion for four-state reconstruction on bounded-degree trees. Not shown: the antiferromagnetic four-state channel. parent of this event

Companion: A capacity criterion for four-state Potts reconstruction on trees evidence for this event

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