N1 — No fourth generation

N1: Prediction

$| gen| = 3$ exactly, from $H_1(τ^3;ℤ) ≅ ℤ^3$ (IV.T171). Any observation of a fourth-generation fermion at any mass scale falsifies $τ$’s topological generation theorem. Experiment: LHC Run 3+, FCC. Timeline: ongoing–2040.

Derivation Context

The number of fermion generations equals the rank of the first integer homology of the $τ^3$ fibration:

The result $|gen| = 3$ is established by three independent arguments, each drawing on different mathematical structures:

• $H_1$ rank = $(τ^3)$ (Theorem (thm:ch60-three-gen-rank)). The first homology group of $τ^3$ has rank 3 by the K"unneth computation (eq:ch60-kunneth). This is the most direct proof: the topological structure of $τ^3$ forces exactly three independent one-cycles.

The fiber $T^2 = (R · S^1) × (ι_τ R · S^1)$ with aspect ratio $r/R = ι_τ$ carries a Laplacian whose primitive eigenvalue spectrum (modes $(n,m)$ with $(n,m) = 1$) supports exactly three stable generation modes below the first composite-mode threshold: $λ_(1,0) = 1$, $λ_(0,1) = ι_τ^-2 ≈ 8.585$, $λ_(1,1) = 1 + ι_τ^-2 ≈ 9.585$. The next primitive mode $(2,1)$ has $λ_(2,1) ≈ 12.58$, exceeding the composite threshold $λ_(2,0) = 4$. No fourth light generation exists. (Registry: IV.T172, Wave 7.)