> Full-text translation from Chinese. The original remains authoritative for its research claims; this translation is not independent mathematical verification.

# SRBRD-17
## Pair-Buchstab Shell / Row-Sieve Quantitative Closure
### Exact Euler-Factor Switching, Dimension-2 Constant Barrier, Prime-Cofactor Row Reduction, and Quantitative Crossing Gate

**Parent program:** RG-SCP / Reverse Goldbach Structural Closure Program  
**Branch:** SRBRD — Symmetric Root-Bounded Relation Domain  
**Round:** SRBRD-17  
**Date:** 2026-09-30  
**Version:** v0.1  
**Authors:** Neo.K; Aletheia (GPT-5.6 Sol)  
**Nature:** Quantitative Sieve Interface / Switching Kernel / Constant-Barrier Audit  
**Prerequisites:** SRBRD-00 through SRBRD-16  
**Status:** Establishes a quantitative provider gate, proves a constant-scale no-go for the naive dimension-2 row upper bound, and exactly switches the semiprime row to prime-cofactor × one-residue sieve; Goldbach remains unproved

---

# 0. This Round Adds No New Closure Layer

SRBRD-16 has established the exact master identity:

$$
\boxed{
M_{PP}
=
|\widehat{\mathcal S}_y|
-
\sum_{y<r\le z_3}
|\mathcal B_r^{pair}|
-
2\sum_{r>z_3}n_r
+
M_{SS}.
}
$$

where:

$$
z_3^3\ge2m-3.
$$

Thus, SRBRD-17 adds no new combinatorial object.

This round asks only:

> If standard dimension-2 lower/upper sieves are inserted directly into these four modules, can the constants cross?

Answer:

$$
\boxed{
\text{naive separate dimension-2 row upper cannot close.}
}
$$

The quantitative source actually required is:

$$
\boxed{
\text{cofactor switching}.
}
$$

Moreover, switching is not heuristic:

> The local Euler factor of SRBRD itself factors exactly as
> $$
> \text{cofactor primality factor}
> \times
> \text{opposite-endpoint factor}.
> $$

---

# 1. Counting Scale

Let:

$$
\boxed{
X=2m-3.
}
$$

Ordered odd-endpoint domain:

$$
3\le x\le X.
$$

Its cardinality:

$$
\boxed{
H=m-2.
}
$$

Thus:

$$
H=\frac{X-1}{2}.
$$

---

# 2. Fixed-Cutoff Bulk

For a cutoff:

$$
z,
$$

define the ordered bulk:

$$
\boxed{
\widehat\Omega_m^{bulk}(z)
=
\left\{
x\in\widehat\Omega_m:
x\ge z^2,
\quad
2m-x\ge z^2
\right\}.
}
$$

Within the bulk,

for every odd prime:

$$
p\le z,
$$

the root condition holds automatically.

Thus:

$$
\operatorname{RootRough}_z(x),
\quad
\operatorname{RootRough}_z(2m-x)
$$

reduces completely to residue avoidance.

---

# 3. Local Forbidden-Class Count

Define:

$$
\boxed{
\nu_m(p)
=
\begin{cases}
1,
&
p\mid m,
\\
2,
&
p\nmid m.
\end{cases}
}
$$

For:

$$
p\ge3.
$$

Reason:

- in general, one must avoid:
  $$
  x\equiv0\pmod p,
  $$
  $$
  x\equiv2m\pmod p;
  $$
- if:
  $$
  p\mid m,
  $$
  the two classes collapse.

---

# 4. Dimension-2 Sieve Product

Define:

$$
\boxed{
V_m(z)
=
\prod_{\substack{
p\in\mathbb P\\
3\le p\le z
}}
\left(
1-\frac{\nu_m(p)}p
\right).
}
$$

This is the canonical local-density product for the ordered SRBRD bulk.

---

# 5. Generic and Center-Divisor Factors

Define the generic product:

$$
\boxed{
V_0(z)
=
\prod_{3\le p\le z}
\left(
1-\frac2p
\right).
}
$$

then:

## Theorem SRBRD-17-T01

$$
\boxed{
V_m(z)
=
V_0(z)
\prod_{\substack{
p\mid m\\
3\le p\le z
}}
\frac{p-1}{p-2}.
}
$$

Thus, center divisors can only:

$$
\boxed{
\text{increase survivor density}.
}
$$

The uniform worst-case local density occurs when small odd center divisors are absent.

---

# 6. Multiplicative Residue Count

For squarefree odd:

$$
d
$$

whose prime factors are all:

$$
\le z,
$$

Define:

$$
\boxed{
\nu_m(d)
=
\prod_{p\mid d}\nu_m(p).
}
$$

In the odd-endpoint parameter,

the bad residue classes modulo:

$$
d
$$

are exactly multiplicative by CRT.

---

# 7. Interval Congruence Remainder

If:

$$
N
$$

is the odd-endpoint count in the bulk,

then:

## Theorem SRBRD-17-T02

for squarefree:

$$
d,
$$

$$
\boxed{
A_d
=
N\frac{\nu_m(d)}d
+
R_d
}
$$

and:

$$
\boxed{
|R_d|\le\nu_m(d).
}
$$

because the count of each forbidden residue class in a finite interval differs from:

$$
N/d
$$

by at most:

$$
1.
$$

This supplies the local model required by a standard finite sieve sequence.

---

# 8. Coarse Lower-Sieve Provider

Choose:

$$
y<z_3.
$$

Use:

$$
\widehat{\mathcal S}_y^{bulk}
=
\widehat{\mathcal S}_y
\cap
\widehat\Omega_m^{bulk}(y).
$$

as a subset of the full survivor set.

If a dimension-2 lower-sieve provider gives:

$$
\boxed{
|\widehat{\mathcal S}_y^{bulk}|
\ge
H_yV_m(y)f_2(s_y)
-
E_y,
}
$$

where:

$$
H_y
=
|\widehat\Omega_m^{bulk}(y)|,
$$

then one can take:

$$
\boxed{
L_y
=
H_yV_m(y)f_2(s_y)
-
E_y.
}
$$

Here:

$$
f_2
$$

denotes the dimension-2 lower-sieve function,

while:

$$
s_y
=
\frac{\log D_y}{\log y}.
$$

---

# 9. DHR Positivity Threshold

External DHR benchmark:

$$
\boxed{
\beta_2
\approx
4.26645.
}
$$

Under the standard normalization:

$$
f_2(s)>0
$$

requires:

$$
s>\beta_2.
$$

Thus, with the natural:

$$
D_y=X^{1-o(1)}
$$

as the distribution level,

choosing:

$$
y=X^{1/u}
$$

requires:

$$
\boxed{
u>\beta_2.
}
$$

---

# 10. Natural Coarse Choice

Therefore:

$$
\boxed{
u\approx5
}
$$

or:

$$
\boxed{
y\approx X^{1/5}
}
$$

is the first simple classical positive lower-sieve region.

This is precisely the SRBRD-16:

# lower-cutoff P4 boundary

---

# 11. Pair-Buchstab Shell Upper Provider

For:

$$
y<r\le z_3,
$$

the shell:

$$
\mathcal B_r^{pair}
$$

represents:

$$
\rho_m(x)=r.
$$

When upper-bounding, left/right tie correction can be ignored,

and the bound split into:

- left endpoint with first factor $r$;
- right endpoint with first factor $r$.

Thus, an abstract provider can be written as:

$$
\boxed{
|\mathcal B_r^{pair}|
\le
U_r^{B,L}
+
U_r^{B,R}.
}
$$

---

# 12. Factored Shell Coordinate

Write the left shell as:

$$
x=ru.
$$

The shell condition requires:

- no prime：
  $$
  p<r
  $$
  obstructs：
  $$
  ru;
  $$
- no prime：
  $$
  p<r
  $$
  obstructs：
  $$
  2m-ru.
  $$

Thus, the shell upper bound is still a dimension-2 sieve,

but the sequence length is approximately:

$$
H/r.
$$

and the sifting cutoff approximately:

$$
r.
$$

---

# 13. Shell Sieve Parameter

Write:

$$
r=X^t.
$$

If the shell distribution level is approximately:

$$
D_r\asymp X/r,
$$

then:

$$
\boxed{
s_B(t)
\approx
\frac{
\log(X/r)
}{
\log r
}
=
\frac{1-t}{t}.
}
$$

For:

$$
t\in[1/u,1/3],
$$

we have:

$$
s_B(t)
\in[2,u-1].
$$

---

# 14. Abstract DHR Shell Upper

Using the dimension-2 upper function:

$$
F_2
$$

to represent it,

the main scale can be formalized as:

$$
\boxed{
U_r^B
\approx
2
\frac Hr
V_m(r)
F_2(s_B(r))
}
$$

plus:

- a finite frontier correction;
- a weighted remainder.

Here the factor:

$$
2
$$

comes from left/right.

In this document, this expression is only a provider template,

not an unconditional asymptotic theorem.

---

# 15. Naive Semiprime-Row Upper

For:

$$
r>z_3,
$$

If one does not use the SRBRD-16 fact that the cofactor is automatically prime,

the row bulk can be treated as:

$$
u
$$

simultaneously avoiding:

- 
  $$
  u\equiv0\pmod p;
  $$
- 
  $$
  u\equiv2mr^{-1}\pmod p.
  $$

in a dimension-2 sieve.

This is the:

# Unswitched Row Sieve

---

# 16. Unswitched Row Parameter

$$
r=X^t,
\qquad
t\in[1/3,1/2].
$$

row length：

$$
\asymp H/r.
$$

cutoff：

$$
z_3\asymp X^{1/3}.
$$

Thus, the natural parameter is:

$$
\boxed{
s_R(t)
\approx
3(1-t).
}
$$

Therefore:

$$
\boxed{
s_R(t)\in[3/2,2].
}
$$

This is exactly the low-$s$ region where the dimension-2 upper sieve is very loose.

---

# 17. External Low-$s$ DHR Upper Function

Under the standard DHR normalization,

For:

$$
0<s\le2,
$$

the published formula is:

$$
\boxed{
F_2(s)
=
\frac{
8e^{2\gamma}
}{
s^2
}.
}
$$

This is an external sieve result.

---

# 18. Continuum Normalization

The following serves only as:

# asymptotic constant diagnostic

not a theorem proved by SRBRD.

Use:

$$
V_m(X^t)
\sim
\frac{
\mathfrak C_m
}{
t^2\log^2X
}
$$

as the dimension-2 Euler-product scale,

and ignore:

- the lower-order endpoint frontier;
- the finite remainder;
- center-divisor cutoff transitions.

---

# 19. Ideal Coarse-minus-Shell Budget

If idealized as:

$$
f_2=F_2=1,
$$

the coarse-mass coefficient is:

$$
u^2.
$$

The Buchstab-shell subtraction coefficient:

$$
2
\int_{1/u}^{1/3}
\frac{dt}{t^3}
=
u^2-9.
$$

Thus:

## Diagnostic SRBRD-17-D01

$$
\boxed{
\text{coarse}
-
\text{shell}
=
9
}
$$

in ideal-density normalization,

and:

$$
u
$$

is independent of this parameter.

---

# 20. Ideal Row Cost

If the row multiplier is also idealized as:

$$
1,
$$

then:

$$
2n_{SP}
$$

has normalized cost:

$$
\boxed{
18
\int_{1/3}^{1/2}
\frac{dt}{t}
=
18\log\frac32.
}
$$

Numerical value:

$$
\boxed{
18\log\frac32
\approx7.29837.
}
$$

---

# 21. Ideal Zero-Transport Margin

Therefore:

## Diagnostic SRBRD-17-D02

$$
\boxed{
9
-
18\log\frac32
\approx
1.70163
>
0.
}
$$

This is very important:

> **The ideal local-density architecture of SRBRD-16's four modules itself has a positive margin.**

Thus, the present failure is not caused by the algebraic identity itself.

---

# 22. DHR Unswitched Row Cost

Substituting T17:

$$
F_2(s)
=
8e^{2\gamma}/s^2
$$

into:

$$
s_R(t)=3(1-t),
$$

the naive DHR row-subtraction coefficient is:

$$
18
\int_{1/3}^{1/2}
\frac{
F_2(3(1-t))
}{t}
dt.
$$

Thus:

$$
=
16e^{2\gamma}
\int_{1/3}^{1/2}
\frac{
dt
}{
t(1-t)^2
}.
$$

---

# 23. Exact Integral

Since:

$$
\frac1{t(1-t)^2}
=
\frac1t
+
\frac1{1-t}
+
\frac1{(1-t)^2},
$$

Thus:

$$
\int_{1/3}^{1/2}
\frac{
dt
}{
t(1-t)^2
}
=
\boxed{
\frac12+\log2.
}
$$

Therefore:

## Diagnostic SRBRD-17-D03

$$
\boxed{
C_{\mathrm{row}}^{DHR}
=
16e^{2\gamma}
\left(
\frac12+\log2
\right)
\approx
60.5588.
}
$$

---

# 24. Quantitative No-Go for Separate Unswitched DHR Rows

The ideal coarse-minus-shell budget leaves at most:

$$
9
$$

at this scale.

But the standard unswitched DHR row upper bound alone already consumes:

$$
\approx60.56.
$$

Thus:

$$
\boxed{
\text{Even with the coarse lower and shell upper idealized,
the naive DHR row upper bound still cannot cross.}
}
$$

The gap is approximately:

$$
\boxed{
60.56-9
\approx51.56
}
$$

normalized units,

before transport is counted.

---

# 25. Why Transport Alone Cannot Be Expected to Repair a 60.56 Constant

In finite controls:

$$
M_{SS}
$$

is a meaningful positive correction,

but its natural scale has the same order as the actual semiprime mass,

rather than being:

$$
O(10)
$$

times larger than the classical row main term.

Thus:

$$
\boxed{
\text{The row-upper provider itself must improve.}
}
$$

All hope cannot be placed in:

$$
M_{SS}.
$$

---

# 26. Prime-Cofactor Switching

SRBRD-16 has proved:

If:

$$
r>z_3,
$$

$$
x=ru\le X,
$$

and:

$$
x
$$

is RootRough$_{z_3}$,

then:

$$
\boxed{
u\in\mathbb P.
}
$$

Moreover:

$$
r,u>z_3
$$

such that:

$$
ru
$$

is automatically RootRough$_{z_3}$ itself.

Thus, the row condition can be simplified.

---

# 27. Exact Switched Row Formula

## Theorem SRBRD-17-T03

For:

$$
r>z_3,
$$

$$
r\le\sqrt X,
$$

we have:

$$
\boxed{
n_r
=
\#
\left\{
u\in\mathbb P:
r\le u\le X/r,
\quad
\operatorname{RootRough}_{z_3}(2m-ru)
\right\}.
}
$$

There is no longer any need to check:

$$
\operatorname{RootRough}_{z_3}(ru).
$$

---

# 28. Switched Local Forbidden Class

Fix:

$$
p\le z_3
$$

as an odd prime.

For a prime cofactor:

$$
u>z_3,
$$

Thus:

$$
u\not\equiv0\pmod p.
$$

The opposite-endpoint obstruction:

$$
p\mid2m-ru
$$

is equivalent to:

$$
u
\equiv
2mr^{-1}
\pmod p.
$$

---

# 29. Center-Divisor Collapse After Switching

If:

$$
p\mid m,
$$

then:

$$
2mr^{-1}
\equiv0\pmod p.
$$

However:

$$
u>z_3\ge p
$$

and:

$$
u
$$

prime，

Thus:

$$
u\not\equiv0\pmod p.
$$

Therefore:

## Theorem SRBRD-17-T04

within a switched row,

the local forbidden-class counts are:

$$
\boxed{
\eta_m(p)
=
\begin{cases}
0,
&
p\mid m,
\\
1,
&
p\nmid m.
\end{cases}
}
$$

This is the:

# Dimension-1 Complement Sieve

---

# 30. Switched Euler Product

Define:

$$
\boxed{
P_0(z)
=
\prod_{3\le p\le z}
\left(
1-\frac1p
\right),
}
$$

and:

$$
\boxed{
W_m(z)
=
\prod_{\substack{
3\le p\le z\\
p\nmid m
}}
\left(
1-\frac1{p-1}
\right).
}
$$

$P_0$ is the local factor for cofactor primality / roughness,

and $W_m$ is the factor for sieving the opposite endpoint within the primes.

---

# 31. Exact Euler-Factor Switching Identity

## Theorem SRBRD-17-T05

For each:

$$
z,
$$

$$
\boxed{
V_m(z)
=
P_0(z)W_m(z).
}
$$

---

# 32. T05 Local Proof

If:

$$
p\nmid m,
$$

$$
\left(
1-\frac1p
\right)
\left(
1-\frac1{p-1}
\right)
=
\frac{p-1}{p}
\frac{p-2}{p-1}
=
1-\frac2p.
$$

If:

$$
p\mid m,
$$

the second factor is absent,

Thus:

$$
\left(
1-\frac1p
\right)\cdot1
=
1-\frac1p.
$$

Multiplying over the primes gives the result.

---

# 33. Meaning of T05

This is not a probability heuristic.

It is an exact Euler-factor identity:

$$
\boxed{
\text{dimension 2 pair density}
=
\text{cofactor-prime density}
\times
\text{one-residue opposite density}.
}
$$

Thus, at the local-density level, cofactor switching:

$$
\boxed{
\text{preserves the original sieve density completely}.
}
$$

It does not replace the problem with another heuristic model.

---

# 34. Switched Row as a Linear Sieve over Primes

T03 + T04 convert:

$$
n_r
$$

into:

> Among prime $u$, avoid, for each:
> $$
> p\le z_3,\quad p\nmid m
> $$
> one nonzero residue class.

Thus:

$$
\boxed{
\text{row sieve dimension}
:
2
\longrightarrow
1.
}
$$

The cost is:

> The base sequence is no longer all integers,
> but primes.

This requires prime distribution in arithmetic progressions.

---

# 35. External Distribution Interface

Typical unconditional interface:

# Bombieri–Vinogradov

supplies prime distribution, averaged over moduli, at approximately:

$$
X^{1/2}
$$

as the level of distribution.

Combined with a linear upper sieve,

this can give a switched row a:

$$
\boxed{
\text{dimension-1 upper bound}.
}
$$

This agrees with the philosophy of Chen switching / weighted sieves.

This round does not claim to have completed the corresponding error analysis.

---

# 36. Switched Row Provider Contract

Define an abstract:

$$
\boxed{
U_r^{sw}
}
$$

such that:

$$
n_r\le U_r^{sw}.
$$

Its intended analytic construction:

1. prime-cofactor range:
   $$
   r\le u\le X/r;
   $$
2. base prime count / prime distribution;
3. local weights:
   $$
   \eta_m(p)=0\text{ or }1;
   $$
4. linear upper sieve with product:
   $$
   W_m(z_3);
   $$
5. an explicit endpoint frontier.

---

# 37. Switched Quantitative Closure

In SRBRD-16 T13, replace:

$$
U_r^{row}
$$

with:

$$
U_r^{sw}.
$$

## Theorem SRBRD-17-T06

If:

$$
\boxed{
L_y
-
\sum_{y<r\le z_3}U_r^B
-
2\sum_{r>z_3}U_r^{sw}
+
L_{SS}
>0,
}
$$

then:

$$
\boxed{
R_G^{-}(2m)>0.
}
$$

T06 is only a provider-composition theorem;

the actual analytic work is to prove each provider.

---

# 38. Finite Product Calibration

The following is computational evidence,

not a bound.

Define the one-sided semiprime count:

$$
\boxed{
U_{SP}^{one}
=
\sum_{r>z_3}
\left[
\pi(X/r)-\pi(r-1)
\right].
}
$$

This counts only possible prime cofactors,

entirely ignoring the opposite RootRough condition.

Multiplying by:

$$
W_m(z_3),
$$

gives:

# Switched Independence Main Term

---

# 39. Calibration: $m=1000$

$$
z_3=13.
$$

$$
U_{SP}^{one}=86.
$$

$$
W_m(13)=0.34375.
$$

Thus:

$$
U_{SP}^{one}W_m
=
29.5625.
$$

actual：

$$
n_{SP}=35.
$$

---

# 40. Calibration: $m=5000$

$$
U_{SP}^{one}=489,
$$

$$
W_m(22)
=
0.304361979\ldots
$$

product：

$$
\boxed{
148.8330\ldots
}
$$

actual：

$$
\boxed{
152.
}
$$

---

# 41. Calibration: $m=10000$

$$
U_{SP}^{one}=1022,
$$

$$
W_m(28)
=
0.29052734375.
$$

product：

$$
\boxed{
296.9190\ldots
}
$$

actual：

$$
291.
$$

---

# 42. Calibration: $m=100000$

$$
U_{SP}^{one}=8856,
$$

$$
W_m(59)
=
0.236288503\ldots
$$

product：

$$
\boxed{
2092.57099\ldots
}
$$

actual：

$$
2100.
$$

---

# 43. Interpretation of the Calibration

For the larger selected controls:

$$
U_{SP}^{one}W_m(z_3)
$$

is very close to the exact:

$$
n_{SP}
$$

as displayed above.

This supports the interpretation that:

$$
\boxed{
W_m(z_3)
}
$$

does capture the main density of opposite-endpoint RootRough survivors.

However:

$$
\boxed{
U_{SP}^{one}W_m
}
$$

is not a rigorous upper bound.

For example:

$$
m=1000
$$

it is below the actual:

$$
35.
$$

Thus, one still needs:

- a sieve multiplier;
- distribution error;
- an endpoint correction.

---

# 44. Coarse Survivor Product Calibration

Selected finite data also show:

$$
|\widehat{\mathcal S}_y|
$$

is close to:

$$
H V_m(y).
$$

For example, the previous audit:

| $m$ | $y$ | $V_m(y)$ | $|\widehat{\mathcal S}_y|/(H V_m(y))$ |
|---:|---:|---:|---:|
| 1000 | 5 | 0.266667 | 1.0070 |
| 5000 | 7 | 0.190476 | 1.0021 |
| 10000 | 8 | 0.190476 | 1.0019 |
| 100000 | 12 | 0.155844 | 1.0000 |

This, too, is only finite calibration.

---

# 45. Cube-Root Survivor Product Calibration

| $m$ | $z_3$ | $V_m(z_3)$ | $|\widehat{\mathcal S}_{z_3}|/(H V_m(z_3))$ |
|---:|---:|---:|---:|
| 1000 | 13 | 0.131868 | 1.0334 |
| 5000 | 22 | 0.104106 | 1.0071 |
| 10000 | 28 | 0.095054 | 1.0038 |
| 100000 | 59 | 0.063222 | 1.0057 |

This explains why the ideal local-density diagnostic fits finite behavior fairly well.

---

# 46. Quantitative Constant Gate

Let the abstract normalized multipliers be:

- coarse lower:
  $$
  L_2(u);
  $$
- shell upper:
  $$
  B_2(t);
  $$
- switched row upper:
  $$
  R_1(t);
  $$
- normalized transport gain:
  $$
  \Phi.
  $$

Then the continuum diagnostic gate is:

$$
\boxed{
\mathcal K(u)
=
u^2L_2(u)
-
2
\int_{1/u}^{1/3}
\frac{
B_2(t)
}{t^3}
dt
-
18
\int_{1/3}^{1/2}
\frac{
R_1(t)
}{t}
dt
+
\Phi.
}
$$

If:

$$
\mathcal K(u)>0
$$

and all asymptotic / remainder providers have been rigorously established,

only then is large-$m$ uniform crossing possible.

---

# 47. Ideal Gate

$$
L_2=B_2=R_1=1,
$$

$$
\Phi=0
$$

in this idealized case:

$$
\boxed{
\mathcal K_{\mathrm{ideal}}
=
9
-
18\log\frac32
\approx1.70163.
}
$$

Thus, the target constant margin is:

$$
\boxed{
\text{small but strictly positive}.
}
$$

---

# 48. Consequence for Provider Quality

Since the ideal margin is only:

$$
\approx1.70,
$$

a quantitative proof cannot tolerate:

- too much loss in the coarse lower bound;
- too much inflation in the shell upper bound;
- a row-upper constant several times the ideal value.

Thus, after SRBRD-17:

$$
\boxed{
\text{constant quality itself is a theorem gate.}
}
$$

A correct big-$O$ order alone is not enough.

---

# 49. Why Standard DHR Row Upper Fails the Gate

Unswitched DHR row contribution:

$$
\approx60.56.
$$

ideal row：

$$
\approx7.30.
$$

ratio：

$$
\boxed{
\approx8.30.
}
$$

Thus, the standard dimension-2 row upper bound is far from the required constant regime.

This quantitatively proves:

$$
\boxed{
\text{Switching is not an optimization;
it is a necessary architectural change.}
}
$$

---

# 50. Shell Provider Is the Next Constant Risk

Even if row switching succeeds,

the pair-Buchstab shell still uses:

$$
s_B(t)\in[2,u-1].
$$

Near:

$$
t=1/3
$$

as the endpoint of the band:

$$
s_B\to2,
$$

the dimension-2 upper factor also becomes looser.

Thus, subsequent work may also need:

- shell switching;
- weighted Buchstab decomposition;
- dyadic treatment;
- exact center-divisor gains.

---

# 51. Three Quantitative Regimes

After SRBRD-17, the analytic work can be divided into:

## Regime A — Low Cutoff

$$
p\le y\approx X^{1/5}.
$$

Use a dimension-2 lower sieve.

## Regime B — Descent Band

$$
y<p\le X^{1/3}.
$$

Use a pair-Buchstab shell upper bound,

requiring constant optimization.

## Regime C — Semiprime Band

$$
X^{1/3}<r\le X^{1/2}.
$$

Do not use a naive dimension-2 upper bound.

Use:

$$
\boxed{
\text{prime-cofactor switching}
+
\text{dimension-1 opposite sieve}.
}
$$

---

# 52. Center-Divisor Bonus Persists Under Switching

If:

$$
p\mid m,
$$

after switching:

$$
\eta_m(p)=0.
$$

Thus:

$$
W_m(z)
$$

completely removes the opposite-endpoint sieve penalty from this prime.

Thus, center divisors simultaneously:

- increase:
  $$
  V_m(z);
  $$
- increase:
  $$
  W_m(z);
  $$
- strengthen the SRBRD-15 transport lock.

Center arithmetic supplies a bonus in both modules.

---

# 53. External Brun–Titchmarsh Interface

For prime capacity in a single progression within a switched row,

Brun–Titchmarsh upper bounds can still be used:

$$
\pi(Y;a,q)
\ll
\frac{
Y
}{
\varphi(q)\log(Y/q)
}.
$$

This suits:

- isolated large moduli;
- the frontier;
- exceptional dyadic ranges.

But obtaining:

$$
W_m(z_3)
$$

as the full product gain,

still requires a multi-prime sieve / switching argument.

---

# 54. External Bombieri–Vinogradov Interface

If a linear upper sieve is applied to prime cofactors,

one needs to control:

$$
u
$$

as primes in average distribution across many moduli.

Bombieri–Vinogradov supplies precisely such unconditional average distribution.

Therefore:

$$
\boxed{
\text{DHR lower}
+
\text{Buchstab}
+
\text{BV-switched linear upper}
+
\text{SRBRD transport}
}
$$

is the most concrete analytic stack currently available.

---

# 55. Relationship to Chen-Type Switching

In Tao's exposition of Chen's theorem,

the central method includes:

- almost-prime decomposition;
- switching;
- the linear sieve;
- Bombieri–Vinogradov-level distribution.

SRBRD-17 has not proved Chen's theorem.

However:

$$
\boxed{
V_m=P_0W_m
}
$$

and exact row switching show:

> The semiprime row of SRBRD naturally requires the same type of switching, rather than incidentally borrowing an external technique.

---

# 56. What Would Count as Real Progress Next

Only completion of at least one of the following is a quantitative advance:

### Gate A

Establish an explicit switched row upper bound:

$$
\boxed{
n_r
\le
U_r^{sw}
}
$$

with an aggregate constant close to the:

$$
W_m(z_3)
$$

main term.

### Gate B

For the pair-Buchstab shell, find a weighted / switched upper bound better than raw DHR:

$$
F_2(s_B)
$$

as displayed above.

### Gate C

Prove that transport:

$$
L_{SS}
$$

supplies a fixed positive constant at the normalized scale.

### Gate D

Insert A+B+C into T06,

and prove:

$$
\boxed{
\mathcal K(u)>0
}
$$

for some：

$$
u>\beta_2.
$$

At present:

$$
\boxed{
A,B,C,D
\text{ have all not yet been completed in full.}
}
$$

---

# 57. Formal Theorem Queue

```yaml
SRBRD_17:
  T01: center_divisor_factorization_of_Vm
  T02: finite_interval_local_remainder
  T03: exact_prime_cofactor_switched_row
  T04: switched_local_dimension_profile
  T05: exact_Euler_factor_switching_V_equals_P0_times_W
  T06: switched_provider_composition_closure
```

---

# 58. External Quantitative Audit Queue

```yaml
ExternalAudit:
  DHR:
    beta2:
      approx: 4.26645
    lower_function:
      f2
    upper_function:
      F2
    low_s_formula:
      F2_s_le_2:
        8*exp(2*gamma)/s^2

  linear_sieve:
    switched_row:
      dimension: 1

  BombieriVinogradov:
    use:
      prime_cofactor_distribution_average

  BrunTitchmarsh:
    use:
      isolated_prime_progression_upper
```

---

# 59. Acceptance Gate

Before SRBRD-17 enters the formal core, the following are needed:

1. exact local factor:
   $$
   \nu_m(p);
   $$
2. exact:
   $$
   V_m=V_0\times\text{center bonus};
   $$
3. an exact interval remainder;
4. the coarse bulk restriction;
5. shell provider clearly conditional on an external sieve theorem;
6. the exact switched-row theorem;
7. the switched forbidden-class theorem;
8. exact Euler factorization:
   $$
   V_m=P_0W_m;
   $$
9. continuum calculations marked as diagnostic;
10. the DHR low-$s$ row no-go not confused with an impossibility theorem;
11. finite calibration not treated as a bound;
12. no Goldbach proof claim.

---

# 60. Verdict

This round can give:

$$
\boxed{
\mathrm{SRBRD\mbox{-}17\ QUANTITATIVE\ SWITCHING\ KERNEL\ PASS}.
}
$$

The two most important results:

## Exact Structural Result

$$
\boxed{
V_m(z)
=
P_0(z)W_m(z).
}
$$

That is:

$$
\boxed{
\text{dimension-2 pair density}
=
\text{cofactor-prime factor}
\times
\text{opposite-endpoint one-residue factor}.
}
$$

## Quantitative Barrier Result

The standard unswitched dimension-2 DHR row upper bound gives, in the natural semiprime band, a normalized cost:

$$
\boxed{
\approx60.56,
}
$$

whereas the total available margin of the ideal architecture is only:

$$
\boxed{
\approx1.70.
}
$$

Thus:

$$
\boxed{
\text{The naive DHR row provider cannot close;
prime-cofactor switching is necessary.}
}
$$

However:

$$
\boxed{
\mathrm{SWITCHED\ UNIFORM\ CONSTANT\ CROSSING\ NOT\ YET\ PROVED}.
}
$$

and:

$$
\boxed{
\mathrm{GOLDBACH\ STILL\ OPEN}.
}
$$

---

# 61. Suggestion for the Next Round

# SRBRD-18
## BV-Switched Row / Weighted Buchstab Constant Closure

The next round should stop expanding the algebra.

Work only on quantitative providers:

### Part A — Switched Row

For:

$$
n_r
=
\#\left\{
u\in\mathbb P:
r\le u\le X/r,
\quad
2m-ru\text{ RootRough}_{z_3}
\right\}
$$

Use:

- Bombieri–Vinogradov;
- the linear upper sieve;
- dyadic $r$ blocks;

to establish an explicit:

$$
U_r^{sw}.
$$

### Part B — Buchstab Band

For:

$$
y<r\le z_3,
$$

obtain a weighted / switched shell upper bound,

reducing:

$$
F_2(s\approx2)
$$

as the source of constant inflation.

### Part C — Constant Ledger

Normalize:

$$
L_y,
\quad
\sum U_r^B,
\quad
2\sum U_r^{sw},
\quad
L_{SS}
$$

all to:

$$
\frac{
\mathfrak C_m H
}{
\log^2X
}
$$

as their scale,

directly yielding a:

# Constant Ledger

The sole question:

$$
\boxed{
\text{Is the total margin }>0?
}
$$

This would be the round currently closest to a genuine analytic crossing test.

---

# Appendix A: Exact Local Factorization

```yaml
local_pair_classes:
  if_p_divides_m:
    nu_m_p: 1
  else:
    nu_m_p: 2

dimension2_product:
  V_m_z:
    product:
      1 - nu_m_p/p

prime_cofactor_factor:
  P0_z:
    product:
      1 - 1/p

opposite_prime_sieve_factor:
  W_m_z:
    for_p_not_dividing_m:
      product:
        1 - 1/(p-1)

identity:
  V_m_z:
    P0_z * W_m_z
```

---

# Appendix B: Ideal Constant Ledger

```yaml
coarse_minus_shell:
  normalized: 9

double_semiprime_row_cost:
  normalized:
    18*log(3/2)
  decimal:
    7.2983719459

zero_transport_margin:
  normalized:
    9 - 18*log(3/2)
  decimal:
    1.7016280541
```

---

# Appendix C: Naive DHR Row Barrier

```yaml
row_parameter:
  t:
    1/3 <= t <= 1/2
  s_R:
    3*(1-t)

DHR_dimension2_upper:
  for_s_le_2:
    F2(s):
      8*exp(2*gamma)/s^2

normalized_double_row_cost:
  exact:
    16*exp(2*gamma)*(1/2+log(2))
  decimal:
    60.5587856961

diagnosis:
  naive_unswitched_DHR_row:
    quantitatively_too_loose: true
```

---

# Appendix D: Switched Row Contract

```yaml
row_r:
  r:
    prime
    z3 < r <= sqrt(X)

exact:
  n_r:
    count_prime_u:
      r <= u <= X/r
      RootRough_z3(2m-r*u)

local_opposite_classes:
  if_p_divides_m:
    forbidden_nonzero_classes: 0
  else:
    forbidden_nonzero_classes: 1

sieve_dimension_after_switch:
  1
```

---

# Appendix E: Finite Switching Calibration

| $m$ | $z_3$ | one-sided prime-cofactor count | $W_m(z_3)$ | product | exact $n_{SP}$ |
|---:|---:|---:|---:|---:|---:|
| 1000 | 13 | 86 | 0.343750 | 29.5625 | 35 |
| 5000 | 22 | 489 | 0.304362 | 148.8330 | 152 |
| 10000 | 28 | 1022 | 0.290527 | 296.9190 | 291 |
| 100000 | 59 | 8856 | 0.236289 | 2092.5710 | 2100 |

**Note:**
`one-sided count × W_m` is only density calibration, not a rigorous upper/lower bound.

---

# Appendix F: Commit Decision

```yaml
research_round: SRBRD-17

decision:
  quantitative_constant_gate: true
  naive_dimension2_row_no_go: true
  exact_prime_cofactor_switching: true
  exact_local_Euler_factor_switching: true
  finite_switching_calibration: true
  switched_uniform_crossing: false
  goldbach_proved: false

next:
  SRBRD-18_BVSwitchedRow_WeightedBuchstab_Constant_Closure
```

---

# References

- H. G. Diamond and H. Halberstam, *A Higher-Dimensional Sieve Method*, Cambridge Tracts in Mathematics 177, Cambridge University Press, 2008.
- C. S. Franze, “Sifting limits for the $\Lambda^2\Lambda^-$ sieve,” *Journal of Number Theory* 131 (2011), 1962–1982.
- A. R. Booker and T. D. Browning, “Square-free values of reducible polynomials,” *Discrete Analysis* 2016:8.
- T. Tao, “254A, Supplement 5: The linear sieve and Chen’s theorem,” 2015.
- Encyclopedia of Mathematics, “Brun–Titchmarsh theorem.”
