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IndisputableMonolith.Numerics.Interval.PhiBounds

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Certified rational endpoint bounds on √5 and on the golden ratio φ = (1+√5)/2. Mass, CKM, neutrino, and interval log/power modules import these inequalities whenever φ-ladder arithmetic must stay inside Lean’s exact rational kernel. Proofs are elementary square comparisons of rationals against 5, then linear transport to φ.

claimStrict rational bounds $a^2 < 5 < b^2$ for explicit positive rationals $a,b$ (e.g. $2.236^2 < 5 < 2.237^2$ and multi-digit refinements), hence $a < \sqrt{5} < b$, and the induced bounds on the golden ratio $\varphi = (1+\sqrt{5})/2$ such as $1.618 < \varphi < 1.6185$ and tighter digit strings.

background

Recognition Science forces φ as the unique self-similar fixed point (forcing step T6). Downstream formulas (mass ladder, electroweak rungs, CKM geometry, observability cutoffs) therefore need concrete numerical control of φ and of √5 without floating-point gaps.

The parent numerics layer (Interval.Basic) supplies verified interval arithmetic whose endpoints are rationals Lean can decide exactly. This module specializes that pattern to the golden-ratio constants imported from Mathlib: compare squares of explicit rationals to the integer 5, obtain strict bounds on √5, then push them through the affine map $x \mapsto (1+x)/2$ to bound φ.

Sibling lemmas come in coarse and fine packs (four-digit and eight-digit style endpoints), so callers can pick the precision they need.

proof idea

Each bound is a short chain. First prove rational square inequalities such as $(2236/1000)^2 < 5$ and $5 < (2237/1000)^2$ by exact integer arithmetic on cleared denominators. Monotonicity of square root on positives yields $2236/1000 < \sqrt{5} < 2237/1000$. Adding 1 and dividing by 2 transports the same endpoints to φ. Tighter packs repeat the pattern with longer decimal rationals. No transcendental analysis is required beyond Mathlib’s √ and goldenRatio definitions.

why it matters in Recognition Science

φ appears in the RS-native constants ($\hbar = \varphi^{-5}$, $G = \varphi^5/\pi$) and in the mass formula yardstick · φ^(rung−8+gap(Z)). This module is the shared numerical substrate for those claims.

Importers include Masses.ElectroweakMasses (Z at rung 1, m_Z ~ φ^51), Masses.Verification (PDG comparison), Physics.CKMGeometry (T11 mixing angles), Physics.ElectronMass.Necessity, Physics.NeutrinoSector, and Astrophysics.ObservabilityLimits (recognition-length cutoffs). Interval modules Log and Pow also import it so exp/log/power enclosures can start from certified φ endpoints rather than ad-hoc floats.

Without these lemmas, every φ-ladder inequality would re-prove the same rational squares.

scope and limits

used by (12)

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depends on (1)

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