Galactic Rotation Curves as a Test Domain for Structuristics: Decompositional Integrity, Structural Regimes, and the Representation Limit of Baryonic Models

This paper tests three structural predictions derived from the Structuristics framework (Moura, 2026) on the SPARC dataset (175 galaxies, 3, 391 data points), using galactic rotation curves as the empirical test domain. The formal mapping is exact: the observed rotation curve is the system behaviour, the baryonic decomposition (gas, disk, bulge) is the Decomposition operator, and the composite baryonic velocity is the Construction operator output. Decompositional Integrity at each radial point is therefore ID = Vbar/Vobs, a direct instantiation of the Structuristics metric in the galactic dynamics domain. Starting from the Radial Acceleration Relation (McGaugh et al. 2016) as the strongest known baryonic model (R² = 0. 877), the paper constructs a corrective model grounded in ID with regime-specific weights. All three structural predictions are confirmed: (P1) the ID radial profile exhibits three distinct structural regimes with empirically identifiable breakpoints; (P2) regime parameters scale continuously with galaxy mass, a fractal-evolutionary signature of mass assembly history encoded in the current structural profile — an original theoretical contribution of this work; (P3) structural groups show systematically different regime profiles, confirming ID as a morphological invariant. A three-layer circularity audit (cross-validation, permutation test, closed model without Vobs) confirms that the genuine non-circular gain is ΔR² = +0. 033, with R²CV = 0. 896, permutation p = 0. 000, and circularity = 0%. The residual gap ΔR² = 0. 064 between the closed and local-ID models is interpreted as the representation limit of the Decomposition operator in the projected rotation curve domain: the information destroyed by 2D projection of a 3D structure. This gap defines the next falsifiable test, T104, which will use IFU kinematic data. Files included: galacticcurvesₛtructuristicsᵥ1₂₀. pdf (main manuscript), galacticcurvesₛtructuristicsᵥ1₂₀. tex (LaTeX source), references. bib (bibliography), figures test₆0ᵥ2, test₉8, test₉9, test₁01, test₁03 (PNG, 180 dpi), scriptsᵦenodoₑn/ (analysis code for T60v2, T95, T98, T99, T100, T101, T102, T103). Methodological note: The investigation followed the CAMAF operational protocol (Moura, 2026), which requires full traceability of the analytical chain, explicit declaration of non-claims, and separation between empirical results, inference, and hypothesis. AI tools were used for script generation, diagnostic interpretation, and manuscript drafting; all scientific decisions were made by the author. See the Transparency Declaration within the manuscript.