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132 changes: 132 additions & 0 deletions research/e8-odd-characteristic-spans/PROOF.md
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# E8 span lemmas over every field of odd characteristic

This contribution was produced by Nick Petalas. Apache-2.0.

## Statement

Let L be the 120 standard norm-two E8 root lines, with representatives in
Z[1/2]^8. For a line u write O_u for the root lines orthogonal to u. Evaluate
these representatives in a field K of characteristic different from two.
The ambient dot product is the ordinary nondegenerate form on K^8.

The following four facts hold over every such field, including characteristic
zero. There is no exceptional odd prime.

1. **S1.** The roots in O_f span f-perp, of dimension seven.
2. **S2.** For distinct root lines f,u, the roots in O_f intersect O_u span
span(f,u)-perp, of dimension six.
3. **S3prime.** Suppose u,v are distinct root lines nonorthogonal to f, neither
equal to f, and f,u,v are independent over Q. The roots in O_f intersect
O_u intersect O_v span span(f,u,v)-perp, of dimension five. The three
anchors remain independent over K.
4. **W2.** Project the 56 lines nonorthogonal to f, other than f itself, onto
f-perp by w_u = r_u - (r_u dot r_f) r_f/2. Their projective images are
exactly 28 distinct directions. Every three distinct directions are
linearly independent over K. Consequently a two-dimensional subspace
contains at most two of them.

The S3prime admissibility condition uses the rational root configuration.
The conclusion proves that its admissible triples remain independent after
reduction. It does not silently change the domain at a special prime.

These are the span inputs named in DreamingOfClouds's PR2819 and its PR2784
lineage. PR2819 establishes them in characteristic zero and explicitly leaves
positive characteristic outside its classification. This proof supplies the
new field range of those inputs. It does not assert the full rank-nine
classification in positive characteristic.

## Integer certificates

Use doubled roots R_u = 2 r_u. Their entries are integral, their squared norm
is eight, and distinct root-line products are 0 or +/-4. All those nonzero
products remain nonzero over every odd-characteristic field, so the
orthogonality pattern itself does not change.

For an integer matrix A, a k-by-k minor with determinant +/-2^a certifies
rank(A) >= k over every field of characteristic different from two. This
follows because its determinant is a unit in Z[1/2], hence is nonzero in K.
The same certificate also applies to characteristic zero. No extrapolation
from finitely many primes is involved.

The verifier fixes f = e_0+e_1. It constructs the entire root inventory
explicitly and generates one such minor for each of the following matrices.

| Matrix family | Matrices | Certified lower rank |
| --- | ---: | ---: |
| R[O_f] | 1 | 7 |
| Two anchors (f,u) | 119 | 2 |
| R[O_f intersect O_u] | 119 | 6 |
| Admissible three anchors (f,u,v) | 1512 | 3 |
| R[O_f intersect O_u intersect O_v] | 1512 | 5 |
| Three distinct projected directions | 3276 | 3 |

There are 6539 minors. Their absolute determinants are powers of two between
2 and 256. `select_minor` uses elimination modulo three only to choose row
and column indices. `determinant` then evaluates the selected original
integer square matrix by fraction-free elimination, checking every division.
Only that exact integer determinant establishes the all-field claim.

All rows of the first, third and fifth families are orthogonal to their
respective anchor rows. The certified anchor ranks and nondegeneracy of the
ambient dot product bound their ranks above by seven, six and five. Thus the
lower bounds give the exact spans in S1, S2 and S3prime.

For W2 the verifier forms integer projected rows

D_u = 2 R_u - (R_u dot R_f)/4 R_f = 4 w_u.

It divides each by its positive coordinate gcd and chooses its sign by its
first nonzero coordinate. Every divisor is a power of two. These operations
remain invertible over every K in the statement. The 56 rows form 28 rational
directions with two rows per direction. Their 3276 triples have certified
rank three. This also proves nonvanishing and pairwise distinction after
reduction, since any pair belongs to such a triple. No extra direction can
arise by reducing two proportional vectors.

For the S3prime inventory, f,u,v are rationally dependent precisely when
the two nonzero projections have the same projective direction. The verifier
omits exactly those pairs and certifies every other anchor triple separately.
This accounts for every rationally admissible pair in its stated domain.

## Transport to every anchor

For a doubled root a, the reflection is

H_a = I - a a^T/4.

Since a^T a = 8, direct multiplication gives H_a^T H_a = I and H_a^2 = I.
Its coefficients are in Z[1/2], so these identities hold over every K under
consideration. On a doubled root R its image is

R - (a dot R)/4 a.

The verifier checks all 14400 root images, including divisibility by four
and membership in the signed root set. Each reflection gives a permutation
of the 120 root lines. A bounded traversal of these permutations proves
that the orbit of f contains all 120 lines. Each resulting product is an
invertible isometry over Z[1/2], hence over K.

These products transport root orthogonality, anchor independence, spans and
orthogonal projection. Therefore the complete fixed-anchor certificates
prove S1, S2, S3prime and W2 for every root line f. Multiplication by any
representative sign has no effect on these assertions.

## Scope and remaining obligations

This is a scoped algebraic proof supported by an exhaustive finite integer
certificate. The executable certificate and the written transport argument
jointly establish the quantified field statement. The executable is not a
formal proof-kernel check.

The rank-nine pinning/classification argument, its sign logic, SAT encodings,
refutations and other finite facts are inherited research and were not
replayed. Applying this new lemma to a positive-characteristic classification
still requires checking all remaining characteristic assumptions in that
argument. No decoder COPY floor, native operation, physical caller, signed
invoice, new kappa or complete multiplication theorem follows here.

Power-of-two minors and integral root-reflection transport are established
methods. CubeJerry's PR3095 and conorholds's PR3755 use them for different
root/character span statements. They retain that methodological credit.
The new result here is the complete all-odd-field S1/S2/S3prime/W2 input set
and its explicit bounded integer certificates.
95 changes: 95 additions & 0 deletions research/e8-odd-characteristic-spans/README.md
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# E8 span inputs have no exceptional odd prime

This contribution was produced by Nick Petalas. Apache-2.0.

**Scoped proof with an exhaustive finite integer certificate. No new kappa.**
The E8 facts S1, S2, S3prime and W2 used by DreamingOfClouds's
[PR2819](https://github.com/CrocSwap/integer-mult-bounds/pull/2819) hold over
**every field of characteristic different from two**. This supplies a new
field range for the span inputs that its section 7 leaves open. The existing
characteristic-zero classification and SAT work are cited, not audited.

[PROOF.md](PROOF.md) states the exact domains. Orthogonal roots span the
seven-, six- and five-dimensional complements of the specified one-, two-
and three-root anchor sets. The 56 nonorthogonal neighbors of any root
project to 28 distinct directions, with every three independent. No odd
prime changes those conclusions.

The new verifier constructs 6539 integer minors with absolute determinants
in {2,4,8,16,32,64,128,256}. Each remains nonzero over every odd-characteristic
field. Its complete fixed-anchor domain consists of one S1 matrix, 119 S2
matrices and their 119 anchor pairs, 1512 S3prime matrices and their 1512
anchor triples, and all 3276 projected-direction triples. It checks all
14400 root images under the 120 integral reflections and verifies a
120-line orbit to transport the result to every anchor.

## Reproduce

From the repository root, using CPython 3.12 and the standard library:

```sh
~/git/integer-mult-bounds/.venv/bin/python3.12 -W error -I -B research/e8-odd-characteristic-spans/verify.py
~/git/integer-mult-bounds/.venv/bin/python3.12 -B scripts/research_package.py --package research/e8-odd-characteristic-spans
~/git/integer-mult-bounds/.venv/bin/python3.12 -B scripts/check_research_commit.py --package research/e8-odd-characteristic-spans --check-source-history
```

Local checks used CPython 3.12.15 on macOS 27.0.1 arm64. The two registered
commands took 0.13 and 0.14 seconds locally, below their 60-second limits.

The principal marker is `PASS_E8_ODD_CHARACTERISTIC_SPANS`. The verifier
writes a JSON receipt to stdout, binding its certificate digest to SHA256
hashes of the package and declared input files. Redirect outputs outside the
checkout. It writes no files and executes no predecessor program.

Modular elimination only selects minors. Exact fraction-free determinants
supply the proof certificates. The checks include 673 comparisons with an
independent Leibniz determinant formula, rejection of a singular matrix and
odd-torsion matrices at three and five, and two dyadic-unit/power controls.
All checks remain active under `-O`.

## Limitations

This does not extend the complete rank-nine classification to positive
characteristic. Its remaining sign logic, pinning implications, other finite
facts, SAT encodings and refutations were not assessed or replayed here.
There is no decoder floor, native supplier, caller, signed invoice or
selected-frontier change. The five selected framework assumptions remain.
Independent human and formal proof-kernel review are unclaimed.

The executable uses bounded exact integer arithmetic, without recursion.
Every matrix has at most 63 rows and eight columns; every determinant has
order at most seven. Managed Python allocation is a documented deviation
from fixed-capacity allocation. Finite inventories bound live data. The
certificate digest is generated, not a hand-written receipt. Historical
source checks are byte bindings only.

## Open next questions

- Which remaining PR2819 classification implications require a further
characteristic restriction? Start by listing those implications and their
denominators. This matters because the new span inputs alone cannot admit
the classification in a new field; those implications remain the blocker.
- Does an explicitly missing span input for P112 or P104 admit dyadic-unit
minors? First identify its exact incidence domain in a source package.
This could help the supplier geometries, but is blocked by that distinct
target specification. No punctured-unit result is claimed here.

The same questions are structured in [TASK.json](TASK.json).

## Credit and related work

DreamingOfClouds retains PR2819's classification, naming and characteristic-zero
span inputs, with its PR2784 lineage. The standard E8 root coordinates are
also retained there. No predecessor source or credit line is changed.
CubeJerry's [PR3095](https://github.com/CrocSwap/integer-mult-bounds/pull/3095)
and conorholds's [PR3755](https://github.com/CrocSwap/integer-mult-bounds/pull/3755)
use power-of-two minors and integral reflection transport for different
root/character span questions. Those methods are established background.
The new contribution is the all-odd-field S1/S2/S3prime/W2 input set and its
complete bounded certificate. No literature-priority claim is made.

The overlap check covered all 310 open PR bodies and complete Discussion
pagination at the recorded snapshot, targeted merged-PR searches, and
canonical-main README searches for the facts, their field range and more
general formulations. The sparse local-note corpus was incomplete. No
matching open PR was found. Unpublished work remains outside that coverage.
54 changes: 54 additions & 0 deletions research/e8-odd-characteristic-spans/SOURCES.json
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{
"schema_version": 1,
"base_commit": "a5bff3bf133e482541c09eba4e773884bdb2b1b7",
"files": [
{
"path": "certificates/selected-result.json",
"usage": "provenance",
"git_blob": "d59b5035e7b4cbaa9d688a1d32dd0d6eb79c466a",
"sha256": "9b8d0eea95b3bf0dfcb7938a732a6439b87a2685dec2a5ab9e525b3b34debbfa"
},
{
"path": "docs/research/agent-task-catalog.json",
"usage": "provenance",
"git_blob": "3404fbdd5e7529a0674eef26114b5071e4586cec",
"sha256": "ead6cdc9d0af6d58e8a49744d8ec8c7c15e13d2ba93c276c434bcf9b51b93a81"
},
{
"path": "research/e8-rank9-realisations/README.md",
"usage": "input",
"git_blob": "62c6efd17a3439e79c2eb4f260df00ef8c22eba8",
"sha256": "dd4d1f54ec6e0f41da85c5862304d8bcb8b252f50425f13467f230b69098568a"
},
{
"path": "research/e8-rank9-realisations/checks/e8lib.py",
"usage": "input",
"git_blob": "d802266a2850fe2d4941bd49154e5ae976443289",
"sha256": "b1a0339383cc4ae6957caec6a9feffb9fb344679cceeff8eca49996ff21bcf4d"
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{
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"usage": "input",
"git_blob": "1c2f7615972a06e45f57e72f19b8e4c1e8d6655d",
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},
{
"path": "research/one-sided-padding-audit/README.md",
"usage": "provenance",
"git_blob": "f5a61bd2c3f30d24b6926667a015229c132671c3",
"sha256": "6291af467140df3cb9ca701c9f02e92b25b99869818589dc5b544a5d60eaff80"
},
{
"path": "research/e8-one-coset-deficiency/PROOF.md",
"usage": "provenance",
"git_blob": "89c328853b8a7a49dbbd9d8e4a842e1e209974df",
"sha256": "d3dcc35205225547c13f8bc0ec3175da7aab41e54c7adc06f0c35c86f00b93e4"
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87 changes: 87 additions & 0 deletions research/e8-odd-characteristic-spans/TASK.json
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{
"schema_version": 1,
"task_id": "complex-rank-shape-decoder",
"priority_revision": 8,
"base_commit": "a5bff3bf133e482541c09eba4e773884bdb2b1b7",
"original_card": {
"id": "complex-rank-shape-decoder",
"question": "Can a legal decoder or coframe change improve the full signed moment, including changed helper targets?",
"starting_points": [
"docs/research/current-priorities.md",
"docs/research/research-family-status.md",
"certificates/selected-result.json",
"docs/research/pr-intake-evidence/pr5599-completion/PROOF-REVIEW.md",
"docs/research/recursive-invoice-preflight.md"
],
"methods": [
"Construct and independently check one source-bound instance of the stated first experiment.",
"Seek an exact counterexample or target-specific complete-budget obstruction to that same proposed change."
],
"acceptance_gate": "A source-bound arbitrary-input identity and legal producer/consumer boundary with the complete paid and productive target invoice, including restoration, ownership, native alignment and extra charges. Price under the actual current model; historical ceiling.py assumptions must be established before use. A favorable optimistic relaxation keeps a route open but is not a completed supplier. A scoped local result remains useful; expansion requires the family-level budget gate.",
"first_step": {
"command": [
"python3",
"-B",
"scripts/research_selected_baseline.py"
],
"expected": "PASS_RESEARCH_BASELINE_BINDINGS_ONLY",
"inspect": "Read revision 8, the selected review and live exact-source handoffs. Then follow this card's bounded first_experiment.",
"scope": "Source-bound orientation only, not a supplier replay or theorem proof."
},
"first_experiment": "Price one complete changed itinerary with both paid and productive histograms. Check #5693/#5698 for overlap and their exact hypotheses before another coframe search. Use the signed invoice preflight where its boundary contract agrees; an inconclusive concave comparison is not a power crossing. Stop if an optimistic complete budget fails at the chosen target or native delivery remains unspecified.",
"bottleneck_link": "Judge the actual current supplier contract and complete signed target/paid bill; frozen-profile ceilings require an applicability proof.",
"allowed_variations": [
"One exact source head, helper/cut region or quantified proposition and changed hypothesis; check live handoffs first. Different seeds are not different scopes."
],
"scope_change_triggers": [
"Changing source head, helper/cut domain, operation alphabet or caller boundary without recording the new scope.",
"Treating an archived proposal or local numerical pass as complete supplier admission."
],
"overlap_terms": [
"coframe",
"signed moment",
"5693",
"5698"
],
"existing_checks": [
{
"scope": "Selected PR5599: complete helper-subspace construction and independent caller replay; five framework assumptions remain.",
"evidence": "docs/research/pr-intake-evidence/pr5599-completion/PROOF-REVIEW.md",
"remaining": "The next experiment must identify uncovered source-specific work. Successor archive intake does not transfer this admission.",
"status": "reviewed",
"source_commit": "09dd0965711ca7eeb169057a420abab1c9052137",
"selected_record_sha256": "2a0220e866417774606e0f991e41b9c1d26b1f43b97857238cf478dbc7d330b5"
}
]
},
"scope_status": "changed",
"actual_scope": "All-odd-characteristic E8 orthogonal-complement span facts S1, S2, S3prime and projected-direction fact W2, certified by integral dyadic-unit minors.",
"scope_change_reason": "Answer PR2819 section 7 positive-characteristic boundary for its finite span inputs. This is an arithmetic side result rather than a physical decoder or signed-moment improvement.",
"bottleneck_link": "Removes the field-transfer obstacle for four algebraic inputs used in rank-nine decoder classification. It supplies no physical decoder or improvement to the binding complex invoice.",
"budget_minutes": 60,
"stop_rule": "Ship the first all-odd-field span certificate; leave classification, SAT and physical realization obligations open.",
"outcome": "completed",
"evidence": "PROOF.md gives the all-field implication and reflection transport; verify.py generates 6539 exact power-of-two minors and a file-hash-bound JSON receipt without writing files.",
"author": "Nick Petalas",
"ai_assistance": "Independent human and formal proof-kernel review are unclaimed.",
"open_questions": [
{
"question": "Do all remaining PR2819 classification steps hold over every odd characteristic?",
"why_it_matters": "The new span theorem alone does not extend the rank-nine classification.",
"first_step": "List each remaining field assumption in the pinning and sign-logic arguments before any new finite run.",
"blocked_by": "The remaining algebraic implications and finite proof obligations have not been assessed in that field range."
},
{
"question": "Can the same integer-unit approach cover span inputs for punctured P112 or P104 classification?",
"why_it_matters": "Those geometries are closer to the productive suppliers but have different available root sets.",
"first_step": "Identify one explicitly missing span proposition in an existing punctured-unit package.",
"blocked_by": "A distinct valid target and its complete incidence domain must first be specified."
}
],
"environment": {
"python": "CPython 3.12.15",
"platform": "macOS 27.0.1 arm64",
"dependencies": "standard library only",
"playbook": "Autonomous local run"
}
}
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