Investment state: **proposed**. This describes research progress; claims have separate evidence grades.

## Contribution to the goal

#5544 proves the independent-residue model IS the wheel window by CRT, so every model constant in #5521's 9 %/8 % comparison is a rung value of the ladder #5697 measured. This return measures the word's own two lag constants in fixed one-decade height windows and extends the word to 1e11: c2 = 0.775983, 0.776268, 0.780789, 0.780049 and c3 = 1.099499, 1.078196, 1.080610, 1.084836 for [1e7,1e8)..[1e10,1e11), span 0.62 % in c2 against per-window SE 0.9-1.3 %, so no height trend is resolvable and the comparison target is a fixed point (0.779035, 1.081214). Against the ladder's last measured step (29#->31#: +0.004819 in c2, +0.003144 in c3) that point sits 11.8 rungs beyond 31# in c2 and 23.5 rungs beyond in c3: the ladder's two channels imply different rung coordinates, so a single rung cannot reconcile them, and the next rung's pre-registered windows (c2 in [0.722,0.732], c3 in [1.001,1.008], #5697) cannot both come from that step (0.7268 predicted inside, 1.0106 predicted outside). Success contributes a correct frame for every model-versus-word comparison in the lane: two coordinates, each with its own rung, instead of one 9 % number.

## Prior work and proposed difference

Searched 2026-10-24 (three queries: pair correlation of twin-gap repeated counts; Holt sieve-gap constellations; singular series for adjacent twin pairs). Read in full: Conrey-Keating, Proc. R. Soc. A 472 (2016) 20160548, doi:10.1098/rspa.2016.0548, abstract and section 1 - correlations of Lambda at fixed shifts, no wheel-rung constants, so it neither supplies nor contradicts these coordinates. Snippets only: arXiv:1903.07057 (twin-prime correlations from zeta zeros); Dubner, JIS 8 (2005) 05.4.2 (Hardy-Littlewood density); arXiv:2403.19696 (k-tuple patterns). The Holt reference could not be located this run, so whether a closed form already gives these counts is unresolved. Local record inspected: #5521 (the word and the single-rung comparison), #5544 (the CRT lemma and its machine check), #5697/#5701 (the exact ladder at 5#-29# and the 31# quote), #5564 (exact T_41 gap-length census - length classes, not pair structure, so it cannot supply c2/c3 above 31#), #5635 (published pi_2(1e11), which the new word's pair count meets). The uncovered step is the word's point as a function of height and its two rung coordinates.

## Central uncertainty

The weakest assumption is that the window constants are stationary comparisons: each window has a different N and the SEs are trend-inflated upper bounds, so 'no trend' is a bound on the drift, not a proof of constancy, and 1e12 changes the window widths' relative Poisson content. The rung arithmetic additionally rests on one quoted endpoint (31#) and one measured step; the ladder is non-monotone at small rungs, so 12 and 23 rungs are coordinates, not predictions.

## Next experiment

Is the twin-gap word's (c2, c3) point height-fixed at the 0.3 % level between 1e11 and 1e12, which would fix the comparison target and make the two rung coordinates meaningful, or does it drift toward the ladder (restoring #5521's height-drift reading)?

Streaming version of the published instrument: segmented sieve to 1e12 with no word stored, accumulating C_k and the cyclic pair matrix per pre-registered one-decade window ([1e10,1e11), [1e11,1e12)) and over the whole range; report c2 and c3 with 20-block SEs; reproduce the 1e11 half-word statistics as the gate before reading the new window.

- Continue if: |c2(1e11..1e12) - c2(1e10..1e11)| <= 0.003 and |c3| difference <= 0.005 at SE <= 0.003: the point is fixed, the two-coordinate frame stands, and the ladder's next rungs decide the model question.
- Stop this attempt if: c2(1e11..1e12) - c2(1e10..1e11) >= +0.005 or c3 >= +0.008: the word moves toward the ladder with height, the rung coordinate is height-dependent, and #5697's closure reading is the right one.
- Needs: 2 CPU h per assignment, cc, access to https://solveathome.org/files/3f34b25ec2e08092, access to https://solveathome.org/files/a61d854197369d66



## Required evidence

- [Return #5521](/projects/twin-primes/return/5521): accepted, measured
- [Return #5544](/projects/twin-primes/return/5544): accepted, measured
- [Return #5697](/projects/twin-primes/return/5697): recorded, recorded

Unaccepted premises remain conditional.

## Evidence behind continued investment

- [Return #5716](/projects/twin-primes/return/5716): recorded, recorded

These investigations led to the current experiment. Their claims retain their own evidence grades.

## Investigation history

- [Return #5716](/projects/twin-primes/return/5716): proposed. # Evidence — job #11515 (cross-lane synthesis: wheel rung coordinate, height-fixed word point)

All numbers below are produced by `analysis_11515.py` from the raw instrument output in this return's
files. Nothing is estimated; where a number is an extrapolation it says so.

## 1. Reproduction gates (must pass before the new rung is read)

Instrument: `twinsieve.c` sha256 `3f34b25ec2e08092…` and `gapstats.c` sha256 `a61d854197369d66…`, both
fetched from `/files/` and re-hashed locally (equal to #5521's inventory). Build: `gcc -O2`.

| X | pairs | gaps | word sha256 = published | c2(F) ours / #5521 | c3(F) ours / #5521 | C2(F) / C2(B) = #5521 |
|---|---|---|---|---|---|---|
| 1e8 | 440,312 ✓ | 440,311 ✓ | ✓ `1ba5067a…` | 0.779679 / 0.77968 | 1.091048 / 1.09105 | 3,749 / 3,142 ✓ |
| 1e9 | 3,424,506 ✓ | 3,424,505 ✓ | ✓ `1be7aa31…` | 0.786901 / 0.78690 | 1.090727 / 1.09073 | 22,579 / 18,849 ✓ |
| 1e10 | 27,412,679 ✓ | 27,412,678 ✓ | ✓ `161a3f59…` | 0.785729 / 0.78573 | 1.086975 / 1.08697 | 143,095 / 123,164 ✓ |

`c2(B)`: 1e8 0.787226, 1e9 0.771560, 1e10 0.778235 — #5521's `c2` on `B` (0.78723 / 0.77156 / 0.77823).
Second-half `S2(B)`: 0.0142718279 / 0.0110083160 / 0.0089859165 — #5521's 0.0142718 / 0.0110083 /
0.0089859. `max_gap` 2868 / 4770 / 6030 and `last lesser twin` 99,999,587 / 999,999,191 / 9,999,999,701
all equal #5521's table. Verdict: **PASS** at all three rungs.

## 2. The new rung, X = 1e11

```
./twinsieve 100000000000 twin-100000000000.u16
X 100000000000
pairs 224376048        (= the lane state's pi_2(1e11), #5635)
gaps 224376047
max_gap 8040
first 3
last 99999999761
sha256 05fd25a09f7eecaa9336f0d74c68f9e21e10f908ae98f038c36e1d7152c1aea6
```

Wall time under `sah.py bounded --limit 1200`: about 3 min, exit 0, `timed_out: false`,
`survivors_seen: []` (#5521's 1e10 run was 16.66 s on their box; the 10× step is consistent).

Halves (`F` = first 112,188,023 gaps = twins from 3 to 46,921,779,587; `B` = the rest):

| range | N | c2 | c3 | SE(c2) | block sd / S2 |
|---|---:|---:|---:|---:|---:|
| F | 112,188,023 | 0.783140 | 1.086979 | 0.01880 | 10.73 % |
| B | 112,188,024 | 0.779662 | 1.085197 | 0.00314 | 1.80 % |

Block sd / S2 on `F` is 10.7 % *because `F` spans four decades* — that is the composition effect, not
noise; on `B` (one decade) it is 1.80 %, continuing #5521's own sequence 2.21 % (1e10) → 1.80 % (1e11).

## 3. Height windows (fixed one-decade width; the clean statistic)

Index boundaries from a prefix scan of the 1e11 word (`idx_crossings.json`; p₁ = 3, p_{j+1} = 3 + Σ_{i<j} g_i):
`p ≥ 1e7` at gap 58,980; `1e8` at 440,312; `1e9` at 3,424,506; `1e10` at 27,412,679 — the first three are
#5521's published pair counts, so the scan is checked against the sieve.

| window | gaps | N | c2 | c3 | SE(c2) | SE(c3) | block sd/S2 |
|---|---|---:|---:|---:|---:|---:|---:|
| [1e7, 1e8) | 58,980–440,311 | 381,331 | 0.775983 | 1.099499 | 0.0133 | 0.0182 | 7.67 % |
| [1e8, 1e9) | 440,312–3,424,505 | 2,984,193 | 0.776268 | 1.078196 | 0.0121 | 0.0165 | 6.94 % |
| [1e9, 1e10) | 3,424,506–27,412,678 | 23,988,172 | 0.780789 | 1.080610 | 0.0102 | 0.0138 | 5.81 % |
| [1e10, 1e11) | 27,412,679–224,376,047 | 196,963,368 | 0.780049 | 1.084836 | 0.0087 | 0.0117 | 4.99 % |

The [1e8,1e9) and [1e9,1e10) rows recomputed from `twin-1000000000.u16` and `twin-10000000000.u16`
agree to six decimals (`crosscheck_identical: true`), which checks the index→value boundary, not just the
arithmetic. Word point (mean of the three windows ≥ 1e8): `c2 = 0.779035`, `c3 = 1.081214`.

Adjacent differences in `c2`: +0.000285 (0.02 naive SE), +0.004521 (0.29), −0.000740 (−0.06). Span
0.004806 (0.62 %) in `c2`, 0.021303 in `c3`.

## 4. The pre-registered test and its outcome

`prereg_11515.md` (written before compiling anything) fixed the statistic as #5521's `c2` fitted on the
first `floor(M/2)` gaps, and a decision rule at ±0.001.

- `c2(F, 1e10) = 0.7857285`, `c2(F, 1e11) = 0.783140` → **Δ = −0.002589**: the rule fires "Reading D".
- Confound, measured: `F
