dm³ 102 · Week 01 · Review

Review — π, φ, and the Operator Chain

What 101 actually established, and what still isn’t proved
dm³ 102 · Week 01 · Review
Review — π, φ, and the Operator Chain
Course: dm³ 102  ·  Review  ·  Source: dm³ 101, Weeks 1–16

Before Phase I of 102, a precise recap — precise on purpose, because 101 spent sixteen weeks distinguishing proved from argued from axiomatic, and that discipline carries forward. The operator chain \(G = U \circ F \circ K \circ C\) is well-defined by construction (Theorem A, proved, 0 sorry). The period \(T^*=2\pi\) is asserted as structure data in AXLE_v6.lean, with its geometric derivation (Reeb-flow compactification) argued in prose, not yet formalized. \(\varphi \approx 1.618\) is the \(n=2\) rung of the recurrence ladder, proved subcritical (Theorem \(\varphi\).1) — it never completes a dm³ fold on its own, and no AXLE Lean file exists for it yet (unlike \(\eta\), which does — this course’s first stop).

The gap this course closes
101 ended at \(\tau - \varphi \approx 0.382\), the distance from the first (subcritical) ladder rung to the embodiment threshold. 102 covers the next three rungs — \(\mu\) (not a ladder rung itself, but the Lyapunov exponent that makes the whole chain converge), \(\eta\) (Tribonacci, \(n=3\), the critical rank), and \(\Delta\) (Tetranacci, \(n=4\), the first supercritical rank). By Week 16 you’ll have covered five of the nine named constants in the full G1–G9 series.

One correction carried forward from 101, worth restating here since it’s easy to misremember: the inner Gronwall basin boundary is \(r^* = 0.77594059\) (\(\approx 0.776\)), numerically certified to 8 decimal places — not the rough \(\approx 0.80\) figure an earlier draft used. The certified value is solid; the general theorem that the basin really is asymmetric (inner_basin_is_asymmetric) is still an axiom in Chain_updated.lean, pending full ODE formalisation. Both facts matter for Week 3.

This week’s content is grounded in the AXLE Lean sources and Book 3 chapters cited above — where a claim rests on an axiom, that is stated explicitly rather than presented as independently verified.
-- dm³ 101 recap, carried forward:
--   Theorem A: G = U∘F∘K∘C well-defined                proved, 0 sorry
--   T* = 2π: structure data                              asserted; Reeb-flow argument prose-only
--   φ ≈ 1.618: subcritical (Theorem φ.1)                 proved (classical); no Lean file
--   r* = 0.77594059                                       certified numerically (8dp)
--   inner_basin_is_asymmetric                             AXIOM, not yet proved
example : True := trivial