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Add roadmap: adic spaces, up to the Fargues–Fontaine curve - #80

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Add roadmap: adic spaces, up to the Fargues–Fontaine curve#80
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CBirkbeck:roadmap/adic-spaces

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@CBirkbeck CBirkbeck commented Jul 22, 2026

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A roadmap for the foundations of Huber's theory of adic spaces (TauCetiRoadmap/AdicSpaces/, README + Suggested.lean): Huber and Tate rings, the valuation spectrum Spv A, continuous valuations and the adic spectrum Spa (A, A⁺), rational localization and the structure presheaf, the sheafiness theorem with Čech acyclicity for strongly noetherian Tate rings (Wedhorn Theorem 8.28(b) / Huber), the definition of adic spaces, and — as the final application (Layer 7 of Layers 0–7) — the adic Fargues–Fontaine curve 𝒳 = 𝒴/φ^ℤ for E = ℚ_p and a perfectoid field F of characteristic p.

Notes

  • Coordination with Mathlib. Open PRs now develop this material — mathlib4#38009 (Spv and its topology on ValuativeRel), mathlib4#42312 (Huber rings), mathlib4#42315 (Spa as a topological space). The roadmap follows the upstream decisions: Spa is a subspace of Spv, points are valuations up to equivalence, and the Layer-0–2 names align with upstream at migration.
  • A⁺ is explicit data. Ring properties (IsHuberRing, IsTateRing, IsStronglyNoetherian, IsUniform) are Prop mixins; theorems take Aplus : Subring A explicitly; a bundled HuberPair (with morphisms carrying continuity and f(A⁺) ⊆ B⁺) serves the categorical uses. No global A⁺ typeclass, and no globally bundled pair.
  • The categories are Wedhorn's ladder: 𝒱^pre (presheafed spaces with stalk valuations) → affinoid pre-adic spaces → pre-adic spaces → 𝒱 (the sheaf subcategory) → adic spaces. Sheafiness comes in three named notions (IsSheafyPair, IsSheafyRing, IsStablySheafyRing), and Layer 4 proves the pair-level sheafiness theorem plus the all-degrees Čech acyclicity actually used by the applications (the H^q-vanishing form of 8.28 needs a Čech-to-sheaf-cohomology comparison; sheaf cohomology is not developed here).
  • Layer 6 states the Buzzard–Verberkmoes theorem and a new counterexample (uniform, sheafy, not stably uniform — answering Hansen–Kedlaya Remark 3.16), proved in AINTLIB's FJP/ directory; its formal status inherits the Layer-4 dependency cone like every downstream result.
  • Layer 7 fixes the direct wandering-slice route for the chart isomorphism in 𝒱^pre (the one genuinely new theorem; the topological charts exist in provenance), lists every hypothesis needed to apply Layer 4 to Kedlaya's interval rings B^I, and states the power-comparability lemma the rank-free window covering rests on.
  • Out of scope: étale cohomology, formal models/GAGA, Berkovich spaces, fibre products, almost/condensed methods, perfectoid spaces and tilting beyond Layer 7's perfectoid-field input, Huber's noetherian-ring-of-definition sheafiness case, and the curve's structure theory (bundles, Harder–Narasimhan, classification, B_dR, general E, the relative and schematic curves) — a successor roadmap.
  • Provenance. AINTLIB dev/adic-spaces @ 59bbbe8ba14a (2026-07-28), with a per-milestone status table in the README separating direct sorry counts from the transitive #print axioms audit required at migration. The sheafiness capstone and Spv spectrality are the main incomplete parts; the quotient-curve topology and interval-ring strands are implemented but inherit that cone.

🤖 Generated with Claude Code

CBirkbeck and others added 5 commits July 22, 2026 00:00
…horn

Six layers on Mathlib's ValuativeRel substrate: Huber/Tate rings (prototyped
seeds: PairOfDefinition, IsHuberRing, IsTateRing; Q_p is Tate, Z_p is not),
Spv and its spectrality, Cont and Spa with rational subsets, rational
localization and the structure presheaf with the category V, the sheafiness
theorem for complete strongly noetherian Tate rings with full-degree Tate
acyclicity, adic spaces as locally-V-isomorphic objects, and the finite-jet
pinching example ([FJP]): a uniform non-noetherian sheafy domain that is not
stably uniform, answering Hansen-Kedlaya Remark 3.16, with Buzzard-Verberkmoes
proved alongside. Provenance pins AINTLIB dev/adic-spaces @ 2e5b1cf6 with a
per-file sorry audit: foundations and the FJP directory sorry-free, the
structure presheaf, Spv spectrality, and acyclicity as the open frontier, and
the 828b sheafiness capstone gated on a dependency-cone axiom audit.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
… closing stress test

The intro now leads with acyclicity-in-all-degrees (sheafiness as its
degree-<=1 shadow) and adic spaces; Layer 6 becomes uniformity + BV with the
finite-jet pinching algebra reframed as a suggested worked example exercising
Layers 0-4, its strong-sheafiness refinement (Cor 5.5) explicitly not a
target.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
…heafy

Layer 3 now defines IsSheafy (A, A+) := IsSheafOfTopologicalRings O_X — the
category-valued sheaf condition in topological commutative rings, glued
sections carrying the topology (Mathlib's sheaf-condition machinery and
TopCommRingCat as substrate; name and shape after the Lean 3 perfectoid
project) — with the finite-rational-cover embedding+gluing form, which is
what the AINTLIB provenance carries, proved equivalent as a named milestone
(Wedhorn 8.16-shape cofinality). Downstream sheafiness proofs (the strongly
noetherian theorem, the FJP transfer) land in the two-part form and reach the
definition of record across the equivalence; the provenance entry records
that migrated capstones are re-expressed accordingly.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
…alisation, not the unavailable preprint

All [FJP] paper citations are removed: the stress test is now specified
self-containedly in Layer 6 with the sorry-free AINTLIB formalisation (the
FJP/ directory and its capstone exports) as its reference — recorded in the
intro, the sources convention (one layer has no paper source, and the
provenance evidences the specification), the Layer-6 bullet, the references
list, the provenance entry, the migration cautions (there is no paper to
consult), and the Suggested.lean Layer-6 comment. Strong sheafiness is now
named by its content rather than a corollary number.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
…it (Layer 7)

Rebuilt around the object the rest of the roadmap exists for. New Layer 7
specifies the curve for E = Q_p and a perfectoid field F of characteristic p
(algebraic closedness deliberately NOT assumed — nothing in the construction
needs it): A_inf as a complete Huber ring in the (p,[w])-adic "weak" topology
with A_inf+ = A_inf; Y as the nonempty open phi-stable locus v(p[w]) != 0,
with a Gauss point exhibited; rank-free radius predicates and the windows;
freeness and wandering; X = Y/phi^Z quasi-compact and T0; Kedlaya's interval
rings B^I strongly noetherian (Thm 4.10) hence sheafy BY LAYER 4 — the
roadmap's own theorem consumed by its summit; the descended phi-invariant
structure presheaf as a sheaf of topological rings and X as a V-object; and
the final clause, local isomorphism in V.

Conventions pinned after an adversarial review: the two Frobenius/point-action
conventions and which gives kappa . phi = p kappa; Y is D(p) cap D([w]), NOT
the analytic locus D(p) cup D([w]); "weak topology" means (p,[w])-adic here;
A+ = A_inf is right for A_inf but not for the Tate charts, where B^{I,+} is
the unit ball of lambda_I and its agreement with the rational-localization
plus ring is a theorem; the kappa-to-interval dictionary is INVERSE, with the
conversion lemma to be proved rather than assumed by notation; the breakpoint
c = (p+1)/2 is ours, not Kedlaya's 1 + 1/p (they agree only at p = 2); the
diagonal-closure model of B^I is faithful only subject to an explicit isometry
checklist, and elements of B^I need not have convergent Witt expansions;
quasi-compact does not mean affinoid; and independence of the pseudouniformizer
must be proved. A caveat flags that the sheafiness theorem is cited as 8.28(b)
here and in provenance while another version of Wedhorn numbers it 8.27(b) —
to be fixed once against the pinned revision.

Provenance re-pinned at dev/adic-spaces @ 59bbbe8b: the FarguesFontaine
directory is 39 files, ~1.9 MB, zero file-level sorries — with the honest
reading that it sits on the Layer-3/4 machinery that is not, and that the
V-level chart isomorphism is specification rather than migration. Structure
theory (bundles, HN, classification, fundamental exact sequence, B_dR/B_cris,
classical points, general E, relative curve, Proj + GAGA) is named as the
successor roadmap in dependency order. Mathlib's Perfectoid/FontaineTheta,
Untilt and BDeRham plus WittVector.Isocrystal are added to the consume list.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
@CBirkbeck CBirkbeck changed the title Add roadmap: adic spaces Add roadmap: adic spaces, up to the Fargues–Fontaine curve Jul 28, 2026
…cord Remark 8.27 as a second route

Checked the source directly: the paper has only one version (v1, 14 Oct 2019),
so the pinned revision is the current text. Definition 8.26 is
sheafy/stably sheafy, Remark 8.27 is the pre-adic-space criterion, and
Theorem 8.28(b) is the strongly-noetherian Tate sheafiness theorem — our
citation and the provenance's Wedhorn828/828b names are correct; an external
review reading a different edition had reported 8.27(b). Two findings folded
in: 8.28 already carries the rational-cover acyclicity clause, so Layer 4's
two headline statements are one theorem in the source; and Remark 8.27 gives
Layer 7 a second route to the summit — a pre-adic space with an affinoid
cover by stably sheafy rings is an adic space, and Kedlaya 4.10 supplies
stable sheafiness — now recorded as a decision to take before starting.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
CBirkbeck and others added 6 commits July 31, 2026 22:03
Updated wording for clarity and consistency in the README.
…review fixes

Reframe: the roadmap develops the theory of adic spaces, and Layer 7
applies it to construct the adic Fargues-Fontaine curve — no summit /
headline / stress-test / division-of-labour language, no file-size
flexing. Substantive corrections from the adversarial pass, each
verified independently: spectrality is Mathlib's bundled SpectralSpace
(the pin already has it, T0Space included — the four-class spelling
missed T0 and the 'Mathlib does not bundle' premise was false); the
kappa-to-rho radius dictionary corrected to the reciprocal form
kappa = alpha/r, window [a,b] <-> rho in [|w|^{1/a}, |w|^{1/b}] (the
two previously displayed forms contradicted each other); the Banach-OMT
non-applicability justified by the right reason (not a Banach space
over a valued field, rather than sigma-compactness); route (b) via
Wedhorn 8.27 priced honestly (pre-adic packaging still needed, plus
quotient permanence of strong noetherianness); the finite-jet sheaf
transfer's localized-Milnor-row and completed-localization steps named
as milestones; Witt-expansion warning stated as a warning. Citation
fixes: Henkel's exact title; Huebner's arXiv:2405.06435 is the 'Adic
spaces' lecture notes; AINTLIB is now Apache-2.0. A stale-edition
Wedhorn renumbering claim from the review was rejected — the README's
existing verified note against arXiv v1 stands.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
…lliam Coram

The fibre-product example is presented as what it is — an interesting
ring built for this roadmap to prove sheafy (and which answers HK
Remark 3.16) — not as a standard named object; 'finite-jet pinching'
naming removed from prose (the provenance's FJP/ file names and Lean
identifiers stay as code labels). The restricted-power-series
development — Mathlib's PowerSeries.IsRestricted and the vendored
Gauss-norm material — is credited to William Coram (verified against
the Mathlib file's author line), with coordination noted.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Nineteen warning triangles and a checkmark removed; the sentences
already say 'do not', 'note', 'must be proved' where it matters, and
the signage was noise on top.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
…re, and prose

Mathematical corrections: the completion map is an embedding only for
Hausdorff A (kernel = closure of 0, dense image stated); strong
noetherianness quantifies over completed algebras, so n = 0 gives
noetherianity of the completion, of A itself only when complete, and
the field case is stated at rank one (BGR 5.2.6); the Tate-ring
openness criterion for rational data is (T)A = A, not the existence of
a unit multiple among the elements; Henkel's open mapping theorem is
stated with its hypotheses and its strictness corollary; Wedhorn's
category ladder is restored (V^pre, affinoid pre-adic, pre-adic, V,
adic), stalks are colimit rings with no claimed topology, and O+ is
defined; sheafiness gets three named notions (pair, ring, stably) with
their relations; Layer 4 claims the Cech-acyclicity theorem rather
than verbatim 8.28's H^q clause; A+ becomes explicit data with a
bundled HuberPair for categorical uses, replacing the PlusSubring
typeclass.

Specification upgrades: the rational-localization universal property
in full (with the plus ring and the strictification milestones); the
five-step flatness bridge; the expanded finite-cover sheaf criterion;
the theorem-level Spv spectrality plan; the gluing specification and
the open-disc cover; the power-comparability lemma behind the windows;
the per-hypothesis list for applying Layer 4 to B^I (endpoint
completions no longer called fields); the perfectoid input list and
the five-step pseudouniformizer-independence theorem; the direct
wandering-slice route fixed for the chart isomorphism, with stable
sheafiness retained as a supporting theorem; the finite-jet example
relabelled a proposed counterexample to Hansen-Kedlaya Remark 3.16
requiring independent review, with its verification requirements.

Coordination: the roadmap now records mathlib4#38009/#42312/#42315
and defers Layer-0-2 names to upstream. Provenance is a status table
with direct-sorry and transitive-audit columns; the pin is unified at
59bbbe8ba14a. Prose rewritten per the review: campaign vocabulary
removed, each layer split into definitions / main results /
dependencies / status. Suggested.lean synced (Layers 0-7, the
coordination note, the three sheafiness names, the counterexample
labelling).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Drop the independent-review requirement: the construction answering
Hansen-Kedlaya Remark 3.16 is proved in the FJP/ directory, and the
only caveat is the Layer-4 dependency-cone audit every downstream
result already carries. The former requirements list becomes the
migration decomposition of what the proof contains.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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