The irrational number varphi = (1+√(5))/2 ≈ 1.618 — the limit of the ratio of consecutive Fibonacci numbers — that governs proportional relationships between Elliott waves. Common derived ratios include 1/varphi ≈ 0.618, varphi^2 ≈ 2.618, and 1 - 1/varphi ≈ 0.382, which appear repeatedly in retracement depths and extension targets.