Phi-Squared β-Shift

symbolic-dynamics · 37 views
symbolic-dynamicssymbolic

What It Is

Greedy β-expansion digits of a random x in [0,1) at base β = φ² = (3+√5)/2 ≈ 2.618. The expansion of 1 is 2·1^∞ (eventually periodic but infinite), so this β-shift is SOFIC BUT NOT a shift of finite type --- the strictly-sofic middle of the Parry trichotomy (SFT ⊂ sofic ⊂ general subshift). Ternary alphabet, entropy log φ² ≈ 0.962. A higher-entropy sofic anchor for the soficity probe, alongside the Golden-Mean β-Shift.

Interpretation

Standard analysis sees: few distinct values; anti-correlated (alternating); blue spectrum (high-frequency power); homoskedastic; monofractal; high-dimensional / space-filling. The atlas finds no named structure, but the source is distinctively extreme on Nonstationarity:change_quantiles_high (+4.2z) — beyond what the standard bank predicts for it.

What standard analysis sees
tail heaviness0.34
asymmetry0.73
occupancy0.11
short-range corr0.15
long-range memory0.19
spectral colour0.90
periodicity0.18
complexity0.56
time-irreversibility0.48
volatility clustering0.11
multifractality0.07
dimensionality1.00
nonstationarity0.20
What the atlas adds
Atlas-extreme metrics the standard bank can’t predict for this source
Nonstationarity:change_quantiles_high+4.2zbank-miss 1.6σ
Zariski:algebraic_residual+2.7zbank-miss 1.7σ
Zariski:residual_slope-2.7zbank-miss 2.4σ

Composition

dtypeuint8
range[0, 255]
unique values3 / 16384
mean ± std92 ± 94.3

Fixed alphabet — only 3 distinct symbols across 16384 samples.

Render Gallery

Atlas Position

Nearest neighborDistance
Moebius Function3.78cross-origin
Free Group F₂ Walk3.82
Codon Usage4.05cross-origin

Open in Atlas →

Which Geometries Light Up

Cayley › Cayley:delta_hyp_normrank 4/3060.2627
Cayley › Cayley:growth_exponentrank 305/3060.6794
Nonstationarity › Nonstationarity:change_quantiles_highrank 4/3060.2350
Zariski › Zariski:algebraic_residualrank 4/3060.0652
Zariski › Zariski:residual_sloperank 304/306-5.7127
in stochastic-process
alphabetical
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