The Algebraic Edge: Exact Constants and the Onset Law of the Almost-Quantum Window
Caleb Weiner
Abstract
Four companion papers located, dissected, generalized, and laddered the excess of the almost-quantum set over NPA level 2 on tilted $I_{mm22}$ functionals. This paper asks why the numbers are what they are, and answers for the bottom of the tilted $I_{3322}$ window: the constants are algebraic all the way down. Three thresholds are proven exactly. The no-signaling-line visibility threshold of $I_{3322}$ is the golden ratio conjugate, $\lambda^*_3 = (\sqrt{5}-1)/2$ (explaining a numerical coincidence between two cost conventions, since $1/\lambda - 1 = \lambda$ precisely at $\varphi$; the same constant appears elsewhere in Bell physics as a critical detection efficiency, with no known derivation connecting the two). The quantum maximum of the $I_{3322}$ correlator part is exactly $5$, attained by a hexagonal configuration -- a non-facet functional whose value appears to be new. The $I_{4422}$ threshold is $\lambda^*_4 = \sqrt{2\sqrt{10}-6}$, the positive root of $x^4 + 12x^2 - 4$, by a symmetrization argument in which two feasibility intervals kiss exactly at the quartic root. Below the window, the flat branch is a theorem: an affine family of zero-slack rational duals proves the gap vanishes identically on $[0, 471/500]$, certified closure gives $\mathrm{gap} \leq 2.3\times10^{-8}$ at $w = 2357/2500$, and certified opening gives $\mathrm{gap} \geq 1.10\times10^{-6}$ at $w = 1889/2000$, so the lower edge lies in $[0.942, 0.9445]$. Inside, ten dual-solver points spanning five orders of magnitude follow the onset law $\mathrm{gap} = \tfrac{1}{2}(w - 2\sqrt{2}/3)^2$ to 1--2%, down to gaps of $5\times10^{-10}$; the coefficient follows from the envelope theorem given the measured unit marginal susceptibility (1.00(2)), and the edge is a staggered pair of bifurcations, level $1{+}AB$ at $w_e = 2\sqrt{2}/3$ and level 2 at $w_e^{L2} = 0.955934(3)$. The edge constant is derived at first order: the flat branch's $1{+}AB$ completion obeys a Clifford--Wick pairing and carries an eight-dimensional relation ideal (the dual hexagon plus five operator sum rules); the marginal mode must break relations to turn on, and the cheapest tilt breaks exactly three while preserving five, at a price certified in both directions by exact arithmetic over $\mathbb{Q}(\sqrt{2})$ to be $8\sqrt{2}/3$ per 4 units of anchor -- hence $2\sqrt{2}/3$. The certificates' entries lie in $\tfrac{1}{6}\mathbb{Z}[\sqrt{2}]$ and $\tfrac{1}{18}\mathbb{Z}[\sqrt{2}]$, extending the series' exact-certificate method beyond the rationals for the first time. A failed derivation route -- a homogenized fractional SDP whose optimum sits at infinity, so that every finite iterate overestimates the edge by $1.7\times10^{-4}$ -- is documented alongside the successes, in the company of the field's own precedent that at this boundary only exact objects adjudicate. Files in this record: the paper (The_Algebraic_Edge.pdf and .tex); the $\mathbb{Q}(\sqrt{2})$ certificate pair for the marginal-price theorem with its standalone verifier (q2_edge_certificates.json, verify_q2_edge.py); the lower-edge theorem's proof objects -- the zero-slack flat-dual family, the rational level-2 flat completion, and the closure/opening pair -- with verifier (edge_bracket_certificates.json, verify_edge_bracket.py); the onset-law data table (onset_table.json); generating scripts (gen_edge_bracket.py, gen_onset_table.py); and a README. Both verifiers require only the Python 3 standard library. Companion records: the certified separation (doi:10.5281/zenodo.21534675), the tilted I3322 window (doi:10.5281/zenodo.21603712), the genericity and necessity tests (doi:10.5281/zenodo.21616031), and the ladder anatomy (doi:10.5281/zenodo.21625241).