Topological Origin of the Exponent 18 in the PDL Gravitational Coupling: K₄, S², and the Periodic Table (version 2)

This paper establishes that the integer exponent 18 appearing in the PDL (Projective Dynamic Logo) gravitational coupling Geff∼εG18G_eff ~ ε_G¹⁸ Geff∼εG18 is a topological necessity rather than a counting choice. The elementary closure of the PDL framework is the complete graph K4K_4 K4 on four vertices and six edges, which — equipped with its four triangular faces — is homeomorphic to the two-sphere S2=∂Δ3S^2 = ∂Δ^3 S2=∂Δ3. The homology H2(S2;Z)≅ZH_2(S^2;Z) Z H2(S2;Z)≅Z imposes a rank deficit of exactly one at each hierarchical transition of the PDL chain complex C0→C1→C2→C3C_0 → C_1 → C_2 → C_3 C0→C1→C2→C3, yielding the exact decomposition 18=6+5+4+318 = 6+5+4+3 18=6+5+4+3. The kernel of the proton-to-nuclear transition map is proved analytically over Q(5)Q(√5) Q(5) to be generated by the valence coherence rval(p)=930r_val(p) = 930 rval(p)=930 — the passive variable that closes internally and does not propagate to the nuclear level. The paper further identifies a common topological ancestor shared by this exponent and the maximum electron count per period of the periodic table (2+6+10=182+6+10 = 18 2+6+10=18): both are invariants of S2S^2 S2 imposed by the three-dimensionality of physical space, the former through the irreducible representations of SO(3)SO(3) SO(3), the latter through the simplicial homology of ∂Δ3∂Δ^3 ∂Δ3. All results are derived without free parameters using exact symbolic arithmetic over Q(5)Q(√5) Q(5).