Structural Challenge Ledger Source Policy

Why source policy matters

The Structural Challenge Ledger is not a wholesale import of every public open-problem list. Public lists are used as raw source feeds. A challenge enters the canonical ledger only when it tests a declared τ obligation: domain semantics, structural recovery, bridge adequacy, explanatory compression, prediction, falsification, or a new route to knowledge.

This page records the source-admission rule for each domain. Each domain follows a distinct curation rule because each domain has a different relationship to socially stabilised public problem surfaces.

Mathematics

Mathematics challenges are not imported from a single master list. The ledger combines three source families:

1. Canonical benchmark problems. Clay Millennium Problems and the Langlands Program. These are externally socially stabilised and carry their own external status.
2. Smale-derived structural challenges. Curated subset of Smale’s 18-problem list, selected because each entry tests arithmetic, computation, dynamics, optimisation, algebraic geometry, or formal limits of intelligence. Items already covered by Clay are not duplicated. Externally solved Smale items become recovery checkpoints rather than open challenges.
3. Foundations & Logic Challenge Set. Curated structural set drawn from socially stabilised foundational programmes and debates: Hilbert-style axiomatisation, Gödel limitation, reverse mathematics, set-theoretic independence, categorical foundations, type-theoretic and univalent foundations, linear logic, paraconsistent logic, model theory, proof theory, computability, and the ontology of mathematical objects.

A τ-native mathematical challenge family is also surfaced as a separate cluster but is not new content: it cross-links existing τ pages (Central Theorem, τ-zeta, τ-topos, address resolution, etc.) so they are visible as challenges.

Exclusion rule. A specialised conjecture enters the canonical mathematics ledger only if it tests a structural obligation of τ. Otherwise it may be retained in a raw-source appendix, cited as adjacent prior art, or folded into a broader challenge family.

Physics

Physics is the only domain where the Structural Challenge Ledger preserves the full external open-problem import. This is deliberate. Physics is the most mature, mathematically formalised, measurement-facing description of reality, and a broad external stress surface is defensible.

The pinned source feed is Wikipedia’s List of unsolved problems in physics, captured at revision 1349830343 (April 19, 2026). 102 named entries are refactored into canonical SCL items, each gaining a ring depth (R0 through R6), a subdomain cluster, a physics-core weight, and prediction/falsification cross-links.

The Structural Challenge Ledger adds two structural projections on top of the wholesale import:

• Ring architecture (R0–R6). Each entry receives a ring-depth label distinguishing foundational physics, sector closure, falsification seams, deep domain-structural questions, emergent collective systems, peripheral imported phenomena, and cross-domain handoffs.
• Subdomain clusters. Eleven clusters group entries by where they sit scientifically rather than by ring depth.

Wholesale import does not imply flat priority. Ring depth determines structural relevance.

A separate τ-native physics audit set of fifteen cross-cutting challenges (PN-01 through PN-15) sits alongside the imported surface. These are not imported from any public list; they are stress tests generated by the framework’s own obligations to translate formal construction into measurable physics without hidden fit, hidden gauge structure, hidden calibration, or uncontrolled bridge assumptions.

Life

Life challenges are not imported wholesale from public open-problem lists. The Wikipedia biology and neuroscience lists are used as raw source feeds for v1.0 historical record (biology revision 1350634388, April 23, 2026; neuroscience revision 1330874647, January 3, 2026), but the canonical ledger is curated by structural relevance.

A challenge enters the canonical ledger only if it tests a declared E₂ obligation: life definition, boundary, origin, substrate generality, code, heredity, metabolism, repair, evolution, morphology, ecology, cognition, artificial life, or life beyond Earth.

The canonical set has 29 entries grouped into five clusters: definition and boundary, origin and substrate, molecular and code architecture, evolution and morphology, and ecology and cognition.

Token-specific, taxon-specific, medically narrow, or historically contingent source items do not define the canonical Life challenge set unless they test a structural obligation of the framework.

Metaphysics / Philosophy

Metaphysics and Philosophy use Wikipedia’s List of philosophical problems as a raw source feed, not as the canonical ledger itself (revision 1338262080, February 14, 2026).

The canonical Metaphysics Structural Challenge Ledger is curated by E₃ structural relevance. A challenge enters the canonical ledger only when it tests the framework’s register architecture, ontic-narrowing requirements, phenomenological correlates, proof-theoretic structure, or commitment boundary.

The canonical set has 29 entries grouped into four clusters: ontology and modality; knowledge, truth, logic, and language; mind, consciousness, selfhood, and agency; normativity, religion, and the proof–commitment boundary.

Source-feed entries may be promoted, merged, demoted to recovery checkpoints, archived as token-level examples, or declared out of scope. Promotion does not imply solution or external acceptance. It means the challenge tests one of the framework’s declared E₃ obligations.

Status grammar

Across all four domains the canonical response statuses are:

• internally_addressed
• partially_addressed (mathematics, physics, life) / partial (metaphysics)
• structurally_constrained
• further_investigation
• backlog
• out_of_scope
• external_recovery_checkpoint — for items where the external community has produced a solution and τ’s response is to recover, illuminate, or compare with that solution rather than claim novelty

Metaphysics adds:

• tau_native — the challenge arises from the τ architecture itself rather than from a public source
• recovery_checkpoint — historically or philosophically useful, but not canonical for E₃

Voice discipline

The ledger does not use “resolved” without qualification. Externally solved problems are labelled externally_solved or routed as external_recovery_checkpoint. Internally addressed problems are clearly distinguished from externally accepted solutions. No challenge page implies external scientific or philosophical consensus.