FPF Reference

    A.19:5.2.2.2 Normalization‑based comparability (≼_normalization)

    Preface node heading:a-19-5-2-2-2-normalization-based-comparability-normalization:28618

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    When two state vectors do not meet the strict conditions for coordinatewise comparison (e.g. they come from different spaces, or the “same” Characteristics are measured on different scales or units), the only sanctioned way to compare them is: normalize, then compare.

    Concretely: if we have state x in CS₁ and state y in CS₂, a normalization‑based comparison is permitted only if the model can cite a set of NormalizationMethodInstanceId(s) under a chosen UNM (per A.19.UNM) that lands the relevant coordinates of x into CS₂ (or lands both into a declared common target space). The result is understood as NCVs (or an ≡_UNM quotient class) per A.19.UNM.

    Comparability rule (normalize-then-compare). We say x ≼normalization y only if, after applying the cited normalization instances to produce a representation of x in CS₂ (or a common target), the mapped state can be compared coordinatewise under ≼_coord. In other words, we never compare raw x and y; we compare after mapping into a common, well-typed space.

    If normalization also crosses reference schemes or planes, the comparison cites an F.9 Bridge with exact endpoints and any CL value, plus the CPM comparison scope and evaluation window. The receiving assurance pattern applies any B.3 consequence; normalization does not silently change meaning or grant comparability.

    Inspectability. Each normalization instance used for comparison is recoverable through its A.19.UNM declaration. C.16 governs measurement and calibration backing. If values differ in scale, reference scheme, or plane, the normalization and Bridge choices and their limitations remain explicit.

    Mnemonic: Never compare before both values are carried into the same well-typed space; never claim the same predicate, scope, plane, or window merely from matching labels.

    Last Updated: 2026-07-30 — upstream FPF commit 308edacf (github.com/ailev/FPF)