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Library / First Principles Framework (FPF) - Core Conceptual Specification
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C.17:5.1 - Diversity and illumination

Diversity_P describes coverage or dispersion of one declared retained set under a named measurement policy. A local policy may, for example:

  • take the average pairwise distance among the admitted members under one declared descriptor map, distance Method, and Scale; or
  • report how much of a declared feature partition is covered, using a stated covering radius or k-cover rule.

Neither construction is universal. The result identifies the retained set and membership rule, measurement-policy and Scale editions, descriptor or feature source editions, distance or covering definition, comparison window, and evidence. A distance matrix or coverage map can show the calculation. When the reading affects a decision, vary a plausible kernel, distance definition, covering threshold, or admitted-member set and report whether the conclusion changes.

For a candidate h and retained set S, the same local policy may use the marginal reading DeltaDiversity_P, also written ΔDiversity_P:

DeltaDiversity_P(h | S) = Diversity_P(S plus h) - Diversity_P(S)

Illumination is a report over Diversity_P, such as a coverage map or QD-score summary. It is telemetry, not a primitive characteristic and not part of the default dominance set. Use C.18 to maintain an Archive or Front and C.19 to state any pool policy that uses these readings.

Optional retained-set readings include:

  • FamilyCoverage: coverage of locally defined families under a named policy and Scale;
  • MinInterFamilyDistance: the smallest distance among declared families, with descriptor map, distance definition, Scale, and family-representation rule;
  • AliasRisk: a near-duplicate or alias diagnostic with collision policy, descriptor source edition, and Scale;
  • DescriptorVector: an optional descriptor payload whose dimensions and interpretation the same local policy declares.

These readings characterize the named set. They do not admit sources, select members, establish universality, or widen applicability. For naming candidate sets, apply F.18’s head-term-family anti-inflation rule rather than restating that lexical rule here.