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docs: clarify full-order Buchholz blocker
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docs/echo-types/overview.md

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@@ -95,7 +95,10 @@ maps can admit different echo types.
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- **Not a theorem of ordinal analysis.** The ordinal-notation /
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Buchholz workstream in this repo (`docs/buchholz-plan.adoc`) is a
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parallel, syntactic development; its relationship to Echo Types
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via `EchoOrdinal.agda` is a bridge, not a reduction.
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via `EchoOrdinal.agda` is a bridge, not a reduction. At present,
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the current admitted Buchholz core has a closed well-foundedness
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route, while the full intended order remains open at the
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shared-binder internalization step.
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- **Not a completed categorical semantics.** See
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`docs/assessment.adoc` for the current M5 verdict.
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docs/echo-types/roadmap.md

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@@ -6,11 +6,12 @@ two identified bottlenecks:
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For current cross-repo progress snapshots, see
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`cross-repo-bridge-status.md`.
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- **Bottleneck B1.** The `--without-K` shared-binder constructor
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block in the Buchholz `_<ᵇ_` order. `wf-<ᵇ` is landed for the
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currently admitted core, but full totality + full-constructor
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well-foundedness remain gated on a K-free treatment of the shared-
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binder cases.
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- **Bottleneck B1.** The remaining gap between the closed
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Veblen/current-core route and the full intended Buchholz order:
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the historically blocked shared-binder shapes in `_<ᵇ_`.
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`wf-<ᵇ` is landed for the currently admitted core, but promoting
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those shapes back into the real order package still needs a
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K-free mediated internalization.
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- **Bottleneck B2.** Tool-scope limitations on adjacent repos
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(`maa-framework/absolute-zero`, `januskey`,
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`tropical-resource-typing`). Blocks end-to-end bridge audits.
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## Proof-assistant-dependent work — gated
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- **[gated on B1]** Full `_<ᵇ_` totality on Buchholz terms.
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Requires the shared-binder constructors, which the current Agda
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2.6.3 `--without-K` blocks via pattern-matching. Either an Agda
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upgrade or a rank-embedding proof strategy unblocks this.
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- **[gated on B1]** Extension of totality + well-foundedness proofs to
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the full constructor set (including shared-binder cases such as
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`<ᵇ-ψα` and `<ᵇ-+2`).
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- **[gated on B1]** Internalize the missing shared-binder shapes as
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actual constructors/comparison principles of the real Buchholz
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order. The current route closes well-foundedness for the admitted
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core, but not yet for the full intended constructor package.
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- **[gated on B1]** Re-close totality/inversion/transitivity and
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well-foundedness for the enlarged order after that internalization,
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including shared-binder cases such as `<ᵇ-ψα` and `<ᵇ-+2`.
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- **[gated on B1]** Ordinal semantics of BT terms: denotation
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`BT → Ordinal` preserving order. Requires a formal `Ordinal` type
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as a prerequisite, which is itself downstream of WF.
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already have in-suite.
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Everything **[gated]** waits for its unblocker. The pack above gives
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3–4 weeks of disciplined parallel work without touching blocked
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paths.
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3–4 weeks of disciplined parallel work without touching the remaining
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full-order Buchholz gap.
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