The single source of truth for "what is in echo-types and where." If you cannot find something, it is indexed here or it does not exist. This file supersedes the navigational role of the scattered overview / roadmap / taxonomy docs (which remain as detail, linked below). Keep it current: every new direction or status change updates this file in the same PR.
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Note
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This is the content/architecture map. For the per-session audit
trail (which finding lives in which 6a2 capture) see ../../INDEX.adoc
— different purpose, complementary.
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- Status legend
- Foundation
- Canonical identity layer
[REAL] - Directions
- Thermodynamic — Landauer/Bennett energy bounds
[REAL] - Buchholz / Veblen ordinals — higher-order number systems
[REAL] - Characteristic / EI — epistemic, choreographic, roles
[REAL] - CNO / absolute-zero
[REAL] - JanusKey reversibility
[REAL] - Ephapax L3 — linear/affine modality bridge
[REAL] - Tropical / Dyadic
[REAL*] - MAA Framework integration
[ROADMAP] - Shannon / information theory
[REAL*]
- Thermodynamic — Landauer/Bennett energy bounds
- Tutorial / pedagogy
[REAL] - Tooling
- Governance — proof-debt & retraction
- Documentation index (canonical vs historical)
- Keeping this current
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Mechanised in Agda |
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Real but partial / graded — see the linked status. |
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Planned/specified, not yet built. |
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Acknowledged gap; explicitly not bridged yet. |
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Claim withdrawn by retraction R-2026-05-18; under a falsifiable earn-back gate (see Governance). |
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Settled as a negative result (do not reopen). |
The canonical state is always origin/main. Local working clones drift
behind — git fetch and read origin/main before trusting any survey.
Echo functor / loss-with-residue. The theory of the structured
remainder of information-losing computation: for f : A → B,
Echo f y := Σ (x : A), (f x ≡ y). [REAL]
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Kernel:
proofs/agda/EchoKernel.agda— the funext-free, postulate-free core (re-export ofEcho+ a pinnedKernel-contract).[REAL]Everything else importsEchotransitively; the kernel-vs-derived classification + funext-free certificate isdocs/echo-types/echo-kernel-note.adoc. -
Proofs:
proofs/agda/Echo.agda,proofs/agda/EchoKernel.agda,proofs/agda/EchoFiberTriangulation.agda, and the derivedEcho*.agdamodules classified indocs/echo-types/echo-kernel-note.adoc. -
Library:
echo-types.agda-lib(depend: standard-library absolute-zero). -
Concept doc:
docs/echo-types/overview.md,docs/echo-types/types-abstract.adoc,docs/echo-types/paper.adoc.
The named-theorem load-bearing artefacts that promote Echo from a useful construction to a named structural object: the canonical fibre-completion functor + one leg of the (equivalence, projection) orthogonal factorisation system on Type. Landed 2026-05-27 under R-2026-05-18 honest-scope discipline — K-free skeletons land here; full HoTT-strength upgrades (contractible / propositional fibres, (-1)-truncation, full ↔) are documented as the next earn-back gates in the Pillar F4 template style.
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Total completion —
A ≃ Σ B (Echo f). The slogan-unlock: every irreversible map’s domain is canonically equivalent to the total space of its echoes.proofs/agda/EchoTotalCompletion.agda. -
Orthogonal factorisation system — every
f : A → Bfactors asA ─encode→ Σ B (Echo f) ─proj₁→ Bwith the left leg an equivalence (the totality theorem above) and the right leg a projection whose fibre atyisEcho f y. Architectural keystone.proofs/agda/EchoOrthogonalFactorizationSystem.agda. -
Image factorisation —
Image f := Σ B (Echo f); the proof- relevant image IS the total Echo space. Three classifications (Surjective, Injective, projection-uniqueness under injectivity).proofs/agda/EchoImageFactorization.agda. -
Image factorisation, (epi, mono) form (2026-05-28) — the (epi, mono) earn-back module, module-parameterised in a truncation interface. Companion to
EchoImageFactorization; the previously-pending (epi, mono) form now lands without committing the kernel to a specific truncation primitive.proofs/agda/EchoImageFactorizationProp.agda. -
Generic no-section —
no-section-of-collapsing-map: for ANY collapsing map with two distinct elements landing on the same image, no section exists. Lifts the previous single-instance result to a structural fact about non-injectivity-at-a-point; recovers the original as a one-line corollary.proofs/agda/EchoNoSectionGeneric.agda. -
Loss taxonomy (function-side) — four-axis classification of
f : A → Bby echo shape: EQUIV ⇒ centre + projection-unique; INJ ⇒ projection-unique; SURJ ⇒ every fibre inhabited; CONST ⇒ section from the entire domain. K-free skeletons across all four.proofs/agda/EchoLossTaxonomy.agda. -
Residue taxonomy (residue-side) —
record ResidueForm f Rpackaging the per-output residue carrier + lowering shared by the eight decoration modules. Eight instances (as of 2026-05-28): the original endpoint pair (trivial (⊤), identity (Echo f)), the generic Σ-cert (echoR-residue),linear-affine-residue, the 2026-05-27 audit-follow-onsindexed-residue
cost-residue, and the 2026-05-28 additionssearch-residue
epistemic-residue. The remaining two decoration modules documented as structurally compatible.proofs/agda/EchoResidueTaxonomy.agda. -
Decoration structure (observation-side) —
record DecorationStructure Gpackaging the seven-field decoration recipe (order + refl + trans + propositionality + join + UMP) shared across the eight decoration modules. Three instances: Graded (3-grade), Linear (2-grade), Access (5-grade).proofs/agda/EchoDecorationStructure.agda. -
Observational equivalence — mode-indexed equality
≡monLEcho. Linear is witness-aware (≡); affine is witness-blind (⊤). Headlinemode-equality-strictly-finer-at-linearexhibits a linear-distinct / affine-equal pair, closing the "affine forgets what linear retains" story at the equality level.proofs/agda/EchoObservationalEquivalence.agda.
Qualified universal property (Pillar F, Gate F5 FULL PASS,
2026-05-27). Three slices in the F4 template (funext as
explicit module parameter, never a postulate; unconditional
pointwise corollaries kept funext-free) earn back the
(equivalence, projection) orthogonal factorisation system on
Type at the qualified level:
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F5-1 —
echo-factorisation-strict (funext) : f ≡ proj₁ ∘ encode f.proofs/agda/EchoOFSUnivF5.agda. -
F5-2 — Diagonal lifting property (Pointwise + Strict modules).
proofs/agda/EchoOFSUnivF5Diag.agda. -
F5-3 — Factorisation uniqueness up to iso (Pointwise
Strict modules) via the composition designφ.to = encode f ∘ g⁻¹.proofs/agda/EchoOFSUnivF5Iso.agda.
Retraction follow-up F-2026-05-27a logged in
docs/retractions.adoc. See docs/echo-types/earn-back-plan.adoc
status entry for the full gate-pass record.
Audience-facing modules (Tier 3, GPT-recommended order, all
landed 2026-05-27). Each generalises one concrete example into
the shape the audience speaks in. All four ship the abstract
record + parametric headline theorems + worked instance
honest-bound matched-negative block.
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Provenance —
Provenancerecord +module ProvenanceTheorems. Workedbool-over-nat-provenancereproducesEchoExampleProvenance.proofs/agda/EchoProvenance.agda. -
Security —
Securityrecord +module SecurityTheorems. Per-region exit collapse + audit-no-recovery (factored throughEchoNoSectionGeneric.no-section-of-collapsing-map). Workedregion-exit-audit-instancereproduces thetutorial/region_exit_audit/RegionExitAudit.agdawalkthrough. Honest-bound: NOT bytes-zeroed / side-channel-safe / tamper-evident / oracle-recovery.proofs/agda/EchoSecurity.agda. -
ProbabilisticSupport —
Samplingrecord +module SamplingTheorems. Marginal non-injectivity, Echo carries which index, residue loses index. Workedbool-indexed-nat-sampling. Honest-bound: NOT measure-preserving / probability monad / Kantorovich / coupling / randomness extraction.proofs/agda/EchoProbabilisticSupport.agda. -
Differential —
Sensitivityrecord +module SensitivityTheorems. Blur non-injectivity, Echo carries which perturbation, residue loses perturbation. Workedbool-perturbed-nat-sensitivity. Honest-bound: NOT ε-DP / Lipschitz bound / noise calibration / adversary model.proofs/agda/EchoDifferential.agda.
Curated suite — single-file entry point. The narrative
deliverable that pulls the Tier-1 / Tier-2 / Tier-3 named theorems
into one readable file. Re-exports load-bearing headlines from
every module under suite-side names; companion remark documents
honest scope at the suite level. External-reader workflow: start
here + read source-module companion remarks for the headlines that
interest you. proofs/agda/EchoCanonicalIdentitySuite.agda.
Consolidation docs (2026-05-27). Two doc-only narratives threading the universal-property and fibration-package stories end-to-end. Each cites the source modules + reading order; no new proofs.
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docs/echo-types/universal-property.adoc— pullback presentation + R-2026-05-18 narrowing + Gate F4 + Gate F5 (full OFS, three slices). Threads the categorical universal-property arc. -
docs/echo-types/fibration-package.adoc—map-over*action
Echo-comp-isoaccumulation +cancel-isocancellation
pentagon coherence. Threads the fibration-side story.
Cementing matched-negatives. Two shadow encodings that have been proposed as adequate substitutes for Echo, now provably aren’t:
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Shannon-entropy non-distinguishing — the fibre-count entropic shadow agrees on
echo-truevsecho-false, while the witness side distinguishes them (matched-negative againstEchoAbstractionBarrier.sigma-distinguishes).proofs/agda/EchoEntropy.agda. -
Linear-logic shallow-encoding gap — the canonical LL
!A := 1shadow admits a section that the sourceLEchoprovably does not.proofs/agda/EchoLLEncoding.agda.
Landauer/Bennett bound shape; ThermodynamicallyReversible(p)
≙ Echo p σ ≃ Echo id σ. Zero-cost (Bennett) proved for every
injective map on any Bishop-finite carrier, and lifted to an
arbitrary carrier with no finiteness at all (K-free subsingleton /
occupancy route), certified faithful against the established count and
instantiated on the genuine infinite absolute-zero Program CNO —
"a CNO dissipates zero Landauer energy" is now a real theorem, not the
historically vacuous claim. The one residual — the quantitative
collapse functional on an infinite carrier, O-THERMO-∞ — is now
[CLOSED-NEG]: its impossibility is mechanised
(collapse-cost-impossible, the doc’s own kill condition discharged
negatively). No open obligation remains for this Direction; tag
advanced [REAL*] → [REAL]. Re-rated B / ~95% in
STABILITY_ANALYSIS §3.3 (was C+ / ~70% then B- / ~90%, 2026-05-18);
the standing B- freeze lifted because O-THERMO-∞ is now discharged
(negatively). The Information-Theory bridge is a separate Direction
(see Shannon entry), not part of this one.
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Proofs:
proofs/agda/EchoThermodynamics.agda,proofs/agda/EchoFiberCount.agda,proofs/agda/EchoThermodynamicsFinite.agda,proofs/agda/EchoThermodynamicsArbitrary.agda,proofs/agda/EchoThermoCollapseImpossible.agda. -
Docs:
docs/ECHO-CNO-BRIDGE.adoc§"Thermodynamic Bridge",docs/STABILITY_ANALYSIS.md§3.3,docs/adjacency/hott-fibers.adoc. -
Build:
just test-thermo.
Staged Buchholz-style collapsing in --safe --without-K.
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Proofs:
proofs/agda/Ordinal/(Buchholz/,Brouwer,CNF,Closure,Psi…,ExtendedOrder,RankPow,RankAdm,RankLex,HeadOmega,HeadOmegaInversion,RankPowDomination,RankPowSlice3(2026-05-28 —NonBzero+ strict-jump bridge
head-Ω lower bound),RankPowSlice3Headline(2026-05-28 — Slice 3 headlinerank-mono-<ᵇ-1-via-head-Ω` closed under a strict-head premise; umbrella case-split bumps `bpsi=bpsi at equal markers` to rank-adm / rank-lex)), `RankLexJointBplus` (2026-05-28 PR #147 — parallel rank with `leftmost-α` discriminator for the bpsi-source- at-equality joint-bplus sub-case; second-component strict-mono at equal first components scaffolded; (a)(b)+(c) assembly completed 2026-05-30 via PRs #165 (b lex-first primitive) + #166 (c `BplusFirstTritrichotomy +first-eq-from-bpsi-source-at- equal-headconsumer-side derivation)),RankMonoUmbrellaSlice4(2026-05-28 PR #149 — narrowed<ᵇ⁻ⁿumbrella record bundling WfCNF endpoints +<ᵇ¹derivation; covers all 10 inherited<ᵇ⁰cases + the strict-head joint-bplus; two shortfalls (<ᵇ-ψΩ≤boundary;<ᵇ-+1at equal-head) pinned as⊤-aliases with explicit lex-rank / rank-lex-jb pointers),RankMonoSameLeft(2026-05-30 PR #167 — Path-3 prototype source-rule enrichment via<ᵇ⁺²-same-left; one-line closure viarank-pow-bplus-right-mono),RankMonoUnion(2026-05-30 PR #168 — architectural realisation: union umbrella<ᵇᵘ = <ᵇ¹ ⊎ <ᵇ⁺²via Sum +[,]mediator; per-extension proof work + structural composition; extension recipe in preamble),RankMonoUnionWfCNF(2026-05-30 PR #169 — WfCNF wrap<ᵇᵘⁿbundling canonical-form invariant alongside the union; mirrors Slice 4’s pattern, propagates automatically through new extensions),RankMonoUnionWF(2026-05-30 PR #170 — Gate 2 closure:WellFounded <ᵇᵘviaSubrelation.wellFounded
On.wellFoundedrank-embedding transport fromwf-<′). -
Docs:
docs/buchholz-plan.adoc,docs/echo-types/buchholz-extended-wf.md,docs/echo-types/buchholz-rank-obstruction.adoc(per-constructor verdict table — see ledger for live count). -
Direct-constructor
<ᵇsame-binder cases (Buchholz item B): status tracked solely in the earn-back ledger (docs/echo-types/earn-back-plan.adoc, row B) anddocs/retractions.adoc(F-2026-05-18b) — off the paper critical path. (Reference-only by design: no status is snapshotted here, so this line never drifts as the ledger moves.)
The echo-invariant line: epistemic structure, choreographies, roles.
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Proofs:
proofs/agda/characteristic/(15 modules —ChoreoInjective,RoleMode,RoleRole,RoleGraded,ModeGraded,NonTruncatable,RecipeNonTriviality,RecipeTheorem, …),proofs/agda/EchoChoreo.agda. -
Docs:
docs/characteristic.adoc,docs/EI2_REPORT.adoc,docs/EI2_READINGS_COMPARISON.adoc,docs/integration-audit.adoc. -
EI-2is[CLOSED-NEG](terminated negative — do not reopen). `RoleRole.agda’s "REAL OBSTRUCTION" is a closed negative result, not debt.
Certified Null Operations = echo types where f = id. absolute-zero is
both a dependency of the core and a bridge target.
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Proofs:
proofs/agda/EchoCNOBridge.agda,MinimalCNO.agda,WorkingCNO.agda. -
Docs:
docs/ECHO-CNO-BRIDGE.adoc,docs/echo-types/cross-repo-bridge-status.md.
Constructive fiber theory ↔ JanusKey "architecturally impossible data loss".
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Proofs:
proofs/agda/EchoJanusBridge.agda. -
Docs:
docs/EchoJanusBridge.md,docs/EchoBridges.md.
Cross-repo navigability marker for the hyperpolymath/ephapax
programming-language project, whose L3 layer (formal/Echo.v, 584
lines, 24 Qed, zero Admitted / zero Axiom) is an explicit Coq
port of EchoLinear.agda + EchoResidue.agda under a K-free /
zero-axiom discipline equivalent to --safe --without-K. The Coq
headlines (mode_le_prop, weaken_collapses_distinction,
affine_canonical, degrade_mode_comp,
no_section_collapse_to_residue) each carry the same theorem as the
Agda counterpart.
Scope is intentionally NARROW: this is import-time documentation
two definitional refl-renames of the load-bearing Agda symbols
under ephapax-L3--prefixed names, so a silent upstream rename
trips Smoke.agda. The cross-repo content correspondence is already
discharged by coqc on the ephapax side; no Lane 4 CI dependency.
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Proofs:
proofs/agda/EchoEphapaxBridge.agda(ephapax-L3-weaken↔EchoLinear.weaken↔ ephapaxformal/Echo.vweaken;ephapax-L3-no-section-collapse↔EchoResidue.no-section-collapse-to-residue↔ ephapaxformal/Echo.v:502-517no_section_collapse_to_residue). -
External corroboration scope: L3 only — ephapax-affine and L1/L2/L4 are NOT mechanised to the same standard (see ephapax
formal/PRESERVATION-DESIGN.md+docs/echo-types/paper.adoc§"Threats to validity").
Bridge domains enumerated in docs/EchoBridges.md (JanusKey / CNO /
Tropical / Dyadic). Dyadic is mechanised; Tropical is named/early.
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Proofs:
proofs/agda/Dyadic.agda,proofs/agda/DyadicEchoBridge.agda. -
Docs:
docs/EchoBridges.md.
Connect echo types with MAA’s reversibility proofs
(maa-echo-equivalence). absolute-zero lives under
…/verification-ecosystem/maa-framework/. Planned, not built.
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Docs:
roadmap.adoc§"Deferred research track",docs/EchoJanusBridge.md.
Partial. The discrete non-distinguishing form lands as
EchoEntropy.agda — the fibre-count shadow (uniform-prior Shannon
surrogate) cannot tell echoes apart at a collapsing point, while
the witness side can. Real-valued H(P) = -Σ p log p, mutual
information, and the Transport/Nyquist (Gate-3) bridge remain
open. See Canonical identity layer for the cementing artefact.
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Proofs:
proofs/agda/EchoEntropy.agda,proofs/agda/examples/Transport.agda. -
Docs:
docs/ECHO-CNO-BRIDGE.adoc(lines ~104, ~254),docs/adjacency/information-flow.adoc,docs/gate-3-canonical.adoc,docs/gate-3-transport-handoff.adoc.
Three worked walkthroughs landing 2026-05-26/27 under tutorial/,
each following the honest-bound + matched-negative discipline
(disclosure at top + NotProved-* ⊤-aliases at bottom). Build with
agda --library-file=/tmp/agda-libs -i . -i proofs/agda tutorial/All.agda.
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Walkthrough 1 — certified region-exit audit (
tutorial/region_exit_audit/). ephapax-L3-style region exit modelled type-level viaEchoLinear.no-section-weaken. Formally-accepted killer-app artefact perroadmap.adoc§"Closed lanes" (Lane 5 close-out 2026-05-30). -
Walkthrough 2 — epistemic erasure (
tutorial/epistemic_erasure/). 4-seed → 2-key KDF with no-section-via-residue lifted fromEchoResidue.no-section-collapse-to-residue. Heads off the "does echo-types prove key zeroing?" category-error question. -
Walkthrough 3 — provenance / debugging (
tutorial/provenance_debugging/). 4-elementStatewith two orthogonal sign bits walked through 3 residue layers. Ships both a section (Layer 1) and its absence (Layer 2), exhibiting the boundary at which type-level recovery flips.
Track-level docs: tutorial/README.adoc, plus per-walkthrough
README.adoc files. Lane policy status: see roadmap.adoc §"Closed
lanes" — Lane 5 closed 2026-05-30 via the formally-accepted
killer-app branch (Walkthrough 1).
Language-agnostic proof-workspace engine (arghda-core, Rust). MVP.
Extracted to its own repository 2026-05-30 (see echo-types#159 for
the move record); was previously in-tree under arghda-core/.
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Docs:
docs/arghda-spec.adoc(in the new repo). -
Relationship to echo-types: motivated by the proof pipeline here but operates on any
--safe --without-KAgda workspace; not a build-dependency.
Mirrors the finite-domain shadow of the Tier-1 + Tier-2 spine + the
unconditional fragment of the F5 OFS earn-back. v0.2.0 (2026-05-27,
pinned to e7dded6) extends the original v0.1.0 coverage (Echo,
EchoResidue, EchoFiberCount, EchoThermodynamics) with seven
new shadows for the canonical-identity spine: EchoTotalCompletion,
EchoOrthogonalFactorizationSystem (unconditional fragment),
EchoImageFactorization, EchoNoSectionGeneric, EchoLossTaxonomy,
EchoEntropy, EchoObservationalEquivalence.
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Registry:
julia-professional-registry(registered via PR #16). -
Scope inheritance: R-2026-05-18 retraction surface NOT mirrored; F5 funext-qualified clauses (uniqueness up to iso, diagonal lifting) NOT mirrored — Julia has no funext, the claims would be vacuous; UIP- and truncation-strength upgrades likewise honestly not mirrored.
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Discipline: falsifies-by-counterexample over concrete finite data; the companion makes no proof claims, the Agda here remains the source of truth. No in-repo CI dependency in either direction.
Bridge-status row: docs/bridges/cross-repo-bridge-status.md
§"EchoTypes.jl executable mirror".
The honesty layer. Read before citing any claim above as final.
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docs/retractions.adoc— R-2026-05-18 retracts the graded-comonad / two-models / conservativity / universal-property framing. Those are[RETRACTED], now a loss-graded reindexing modality; earn-back is gated, claims stay retracted until a gate passes. -
docs/echo-types/earn-back-plan.adoc— the consolidated proof-debt ledger + falsifiable gates F1–F4 (F1 = make-or-break graded comonad; F2/F4 independent; F3 gated on F1). Current SoT for what is / isn’t proven. Current gate modules onmainincludeproofs/agda/EchoGradedComonadF1.agda,proofs/agda/EchoPullbackUnivF4.agda,proofs/agda/EchoStepNDModelF2.agda,proofs/agda/EchoGradedComonadInterface.agda,proofs/agda/EchoGradedComonadInstance1.agda, andproofs/agda/EchoGradedComonadInstance2.agda, each scoped by the ledger. -
Gate handoffs:
docs/gate-1-distinct-phenomenon.adoc,docs/gate-2-handoff.adoc,docs/gate-3-*.adoc.
Multiple overlapping docs exist. Use the canonical column; the rest are kept for history and may overclaim (pre-retraction).
| Topic | Canonical (use this) | Historical / superseded |
|---|---|---|
Project map (this file) |
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Proof status / roadmap |
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Concept / definition |
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Bridges |
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Adjacency / related theory |
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— |
This is a living document. Whenever a direction is added, a gate passes/fails, or a claim is retracted/earned-back:
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Update the relevant Directions/Governance entry and its status tag here, in the same PR as the change.
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Never duplicate detail — link to the canonical proof module / doc.
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The GitHub wiki
Homemirrors this file and must point back here as SoT; do not fork content into the wiki.