Explanation of phi_equation in IndisputableMonolith.Foundation.PhiForcing
(1) Plain English
The declaration proves that the golden ratio φ = (1 + √5)/2 satisfies φ² = φ + 1. This is the defining algebraic property of φ.
(2) Why It Matters in Recognition Science
In RS, φ arises as the unique positive scale ratio forced by self-similarity on a discrete J-cost ledger. The equation is the algebraic core that lets the framework derive constants (e.g., ħ = φ^{-5}) and structures (φ-ladder) without free parameters. It is the key step in the forcing chain from discreteness and ledger to φ.
(3) How to Read the Formal Statement
theorem phi_equation : φ^2 = φ + 1 := by
simp only [φ, sq]
have h5 : (0 : ℝ) ≤ 5 := by norm_num
have hsq5 : Real.sqrt 5 ^ 2 = 5 := Real.sq_sqrt h5
field_simp
nlinarith [Real.sq_sqrt h5, sq_nonneg (Real.sqrt 5)]
In standard notation: let φ ≔ (1 + √5)/2; then φ² = φ + 1. The proof reduces the definition, applies the square-root identity √5² = 5, clears denominators, and uses linear arithmetic to close the equality.
(4) Visible Dependencies or Certificates
The proof relies only on Mathlib tactics (norm_num, field_simp, nlinarith) and the definition of φ inside the same module. No external RS axioms are used. Related declarations in the supplied source include phi_pos (positivity) and phi_inv (reciprocal identity). The module imports Cost, LawOfExistence, DiscretenessForcing, LedgerForcing and PhiForcingDerived, but the equation itself is self-contained.
(5) What This Declaration Does Not Prove
It does not prove that φ is forced by a discrete ledger or self-similarity; those steps appear in self_similar_forces_golden_constraint and phi_forced. It also does not establish uniqueness across all positive reals (see golden_constraint_unique) or connections to frequency ladders or zeta symmetries in other modules.