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feat: add Shafarevich relation-rank bound eval problem#387

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feat/shafarevich-relation-rank-bound
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feat: add Shafarevich relation-rank bound eval problem#387
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feat/shafarevich-relation-rank-bound

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@kim-em kim-em commented Jun 3, 2026

This PR adds Shafarevich's relation-rank bound for the maximal unramified pro-p extension of a number field, in the odd-p, empty-S specialization, as an eval problem: with G = Gal(F^{un,p}/F), the relation rank r(G) = dim_{𝔽_p} H²(G; 𝔽_p) is finite and r(G) ≤ d(G) + (r₁ + r₂ - 1) + δ_p(F), where d(G) is the generator rank, r₁/r₂ count the real/complex places of F, and δ_p(F) = 1 iff F contains a primitive p-th root of unity. This is the second of the two external inputs taken as a hypothesis in Logical Intelligence's formalization of the disproof of Erdős's unit-distance conjecture (erdos-unit-distance, Hyp_ShafarevichRelationRankBound), and is not yet in Mathlib.

Unlike the companion Martinet and Golod–Shafarevich problems, this one rests on substantial trusted scaffolding (non-holes): the bespoke construction MaxUnramifiedProPGaloisGroup (with IsEverywhereUnramified and maximalUnramifiedProPF) fixing Gal(F^{un,p}/F), plus the rank definitions generatorRank, relationRank, H2Finite. A solver proves the inequality about these definitions, so their correctness is part of the trusted statement — the manifest discloses this, and notes that the source development's maximality/universal-property lemmas are not shipped here. The statement was checked for faithfulness against Mayer's Theorem 5.1 (S = ∅) and Koch 11.5/11.8 by an independent review (the corrected r₁+r₂-1 unit-rank term and the δ_p root-of-unity correction are present); the module builds with only the expected sorry.

🤖 Prepared with Claude Code

Add Shafarevich's relation-rank bound for the maximal unramified pro-p
extension of a number field (odd p, empty-S specialization): with
G = Gal(F^{un,p}/F), the relation rank r(G) = dim H^2(G; F_p) is finite
and r(G) <= d(G) + (r_1 + r_2 - 1) + delta_p(F). This is the second of
the two external inputs taken as a hypothesis in Logical Intelligence's
formalization of the disproof of Erdos's unit-distance conjecture
(Hyp_ShafarevichRelationRankBound), and is not yet available in Mathlib.

The statement rests on substantial trusted scaffolding (non-holes): the
construction MaxUnramifiedProPGaloisGroup fixing Gal(F^{un,p}/F), and the
rank definitions generatorRank, relationRank, H2Finite. A solver proves
the inequality about these definitions.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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