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Stagnation

As explained in Evolutionary Deep Learning: Genetic algorithms and neural networks

Stagnation is a period during which an evolutionary species shows no discernible improvement in fitness.

Stagnation is a period in which an evolutionary species shows no discernible improvement in fitness. In NEAT, stagnation helps determine when a species has remained unproductive long enough to consider extinction. section 10.5.1

Configure stagnation alongside speciation controls:

  • Set max_stagnation to the number of generations allowed before checking a species for extinction. section 10.5.1
  • Interpret stagnation with compatibility_threshold, which controls how networks are grouped into species. section 10.5.1

How Evolutionary Deep Learning: Genetic algorithms and neural networks covers it

How deep it goes
Defines stagnation and exposes max_stagnation as a configuration interval, without detailing the extinction procedure.
Examples
Uses max_stagnation = 25 in a NEAT circles-classification configuration.
What it assumes
Assumes familiarity with evolutionary networks, species, fitness evaluation, and NEAT compatibility thresholds.
What you can do after
Operate NEAT by configuring the generations allowed before species-extinction checks.
How it connects
Connects stagnation with NEAT speciation, species fitness, compatibility thresholds, mutation, and extinction.

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This explainer was generated by Manning's knowledge graph from the text of Evolutionary Deep Learning: Genetic algorithms and neural networks. The section links point to the parts of the book it draws on.