Persistent Homology

Holes, loops, connected components, topological persistence
topologicaldim topological6 metrics

What It Measures

How many holes and connected components survive as you zoom out -- the topological skeleton that persists across scales.

Delay-embeds the signal into 2D, deduplicates the point cloud, then builds a Vietoris-Rips filtration: imagine inflating a ball around every point and tracking when components merge (H0) and when loops form and fill in (H1). Features that persist across a wide range of scales are topologically robust. Features that blink in and out are noise. The distribution of lifetimes, their entropy, and the total persistence mass characterize the signal's topological complexity.

Metrics

n_significant_features

Count of H0 features with lifetime above 0.1. Dice Rolls (34.1) produces the most significant components -- its random jumps create many well-separated clusters that merge at different scales. Intermittent Silence (24.9) and Collatz Stopping Times (20.8) follow. Rössler (1.0) has just one significant component -- its attractor is a single connected blob in the delay embedding.

h1_total_persistence

Total lifetime mass of all H1 (loop) features. Dice Rolls (1.83) dominates, with loops forming at many scales as its scattered point cloud creates ring-like structures during filtration. Collatz Gap Lengths (0.56) and Codon Usage (0.54) have modest loop structure. Logistic Chaos and Tent Map score 0.0 -- their dense, space-filling attractors leave no room for persistent loops.

max_h1_lifetime

Lifetime of the single most persistent loop. Rule 30 (0.414), Symbolic Lorenz (0.414), and Morse Code (0.414) share the top score -- their binary-valued signals create specific point-cloud geometries in delay embedding where one dominant loop persists across scales. This metric identifies signals with a single robust circular or toroidal structure.

persistence_entropy

Shannon entropy of the lifetime distribution. High entropy means the topological features have diverse lifetimes (no single scale dominates). Low entropy means one feature dominates all others. This separates multi-scale signals from those with a single characteristic scale.

max_lifetime

Lifetime of the single most persistent H0 feature (connected component). Dice Rolls, L-System Dragon, and Rule 110 all hit 1.414 (= sqrt(2), the maximum distance in the unit square delay embedding). Henon Near-Crisis (0.75) has the shortest maximum lifetime — its attractor is compact, so the last two components merge early. This measures the geometric diameter of the delay-embedded point cloud.

total_persistence

Sum of all H0 feature lifetimes. Dice Rolls (8.04) has the highest total — many well-separated clusters, each persisting for a long time. Constants and Quantum Walk score 1.0 (a single component with unit lifetime). This is an integral measure of topological complexity: it weights both the number and duration of connected components.

Atlas Rankings

h1_total_persistence
SourceDomainValue
Dice Rollsexotic1.7809
Partition Functionnumber_theory1.5740
Moebius Functionnumber_theory0.8284
···
Logistic Chaoschaos0.0000
Tent Mapchaos0.0000
Sawtooth Wavewaveform0.0000
max_h1_lifetime
SourceDomainValue
Morse Codewaveform0.4142
Liouville Functionnumber_theory0.4142
L-System (Dragon Curve)exotic0.4142
···
Logistic Chaoschaos0.0000
Tent Mapchaos0.0000
Sawtooth Wavewaveform0.0000
max_lifetime
SourceDomainValue
Pell Wordexotic1.4142
Morse Codewaveform1.4142
Dice Rollsexotic1.4142
···
LIGO Hanfordastro0.0000
LIGO Livingstonastro0.0000
Noisy Period-2chaos0.5630
n_significant_features
SourceDomainValue
Dice Rollsexotic33.7000
A5 Artin a_pnumber_theory25.4000
Partition Functionnumber_theory24.6000
···
LIGO Hanfordastro0.0000
LIGO Livingstonastro0.0000
Sine Wavewaveform1.0000
persistence_entropy
SourceDomainValue
Poisson Countsexotic5.1722
Human Proteomebio5.0500
Catalan G Digitsnumber_theory4.9885
···
Mian-Chowlanumber_theory0.0000
OTOC Growthquantum0.0000
PID Controllerexotic0.2738
total_persistence
SourceDomainValue
Dice Rollsexotic7.9542
Partition Functionnumber_theory7.3142
Markov Chain (10-state)exotic6.1449
···
LIGO Hanfordastro0.0000
LIGO Livingstonastro0.0000
OTOC Growthquantum1.0000

When It Lights Up

Persistent Homology is the atlas's most direct topological detector. The n_significant_features metric uniquely identifies signals with complex multi-component structure -- Dice Rolls, Intermittent Silence, and Collatz Stopping Times form a cluster that no other geometry highlights. The H1 metrics separate signals with genuine loop topology from those that are simply connected, a distinction only available through filtration-based analysis.

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