Pith. sign in
module module moderate

IndisputableMonolith.Cost.TraceRationalExponent

show as:
view Lean formalization →

Number-theoretic support for Cost: no rational square root of five, the golden unit squared has trace three, and rational traces on powers force positive-integer exponents. Real character factorization imports the package. Proofs mix five-adic valuation parity, Z[φ] coordinate expansions, and a six-exponentials-style input bundle.

claimPackage of lemmas: $\sqrt{5}\notin\mathbb{Q}$; $\varphi^2$ has field trace $3$; powers of the golden unit expand with integer coordinates; if a power has rational trace then the exponent is a positive integer (via rationality of coordinates and a six-exponentials trace input).

background

In the Cost layer, real characters and factorization identities are constrained by the arithmetic of the golden unit $\varphi=(1+\sqrt{5})/2$. Its minimal polynomial is $x^2-x-1$; powers live in $\mathbb{Z}[\varphi]$ and admit unique coordinates relative to the basis ${1,\varphi}$. The field trace of $\varphi^2$ is $3$, so rational-trace hypotheses sit on a concrete integer.

The module isolates the elementary Diophantine facts needed before any analytic character identity: five is not a rational square (five-adic valuation is odd), and rationality of a trace propagates to rationality of the coordinate pair of the corresponding power. Those coordinate facts feed an integer-exponent conclusion.

A bundled input shape for six-exponentials-type reasoning appears as a named structure, so downstream factorization can cite a single arithmetic package rather than re-proving valuation and coordinate lemmas in place.

proof idea

The module is a lemma cluster, not a single theorem. no_rational_sqrt_five is a pure valuation argument: $v_5$ of a square is even while $v_5(5)=1$. Trace three for the golden square is a direct expansion of $\varphi^2$. Coordinate lemmas equate powers with their $\mathbb{Z}$-basis coefficients and show that a rational trace forces those coefficients (hence the power) to be rational when the exponent is rational. The integer-exponent theorem assembles those facts with the six-exponentials input bundle to conclude the exponent is a positive integer. No single master proof; each sibling is short and self-contained.

why it matters in Recognition Science

Real character factorization in Cost imports this module. Without ruling out non-integer rational exponents on trace-rational golden powers, character identities could admit spurious rational scalings that break the unique J-cost and $\varphi$-ladder normalization used upstream in the forcing chain (T5–T6). The five-adic lemma closes the quadratic irrationality gap for $\sqrt{5}$; the trace-three and coordinate lemmas pin the arithmetic of $\varphi^n$; the exponent theorem supplies the integrality step factorization needs. Scaffolding elsewhere in Cost can treat integer exponents as discharged once this import is in place.

scope and limits

used by (1)

From the project-wide theorem graph. These declarations reference this one in their body.

declarations in this module (8)