dm³ 102 · Week 08 · Milestone

Milestone III — Deriving the Fold by Hand

Reproduce Theorem C.1 from scratch, then connect it to Collatz precisely
dm³ 102 · Week 08 · Milestone
Milestone III — Deriving the Fold by Hand
Course: dm³ 102  ·  Milestone  ·  Source: Book 3, Criticality Bridge (Theorem C.1)

Milestone task, two parts. Part 1: starting only from \(V(q)=q^3-cq\), derive \(c^*=3\) as the unique value producing a double root at \(q=1\) — the full argument from Week 7, reproduced without looking it up: find \(V'(q)\), solve for the critical point, impose \(q^*=1\), solve for \(c\), verify \(V''(1)\neq0\), factor \(V(q)+2\). Part 2: write one paragraph connecting this to the Collatz map precisely — not just “Collatz has \(c=3\) too” as a slogan, but stating exactly what “coefficient\(=3\)” means for the odd branch \(T(n)=3n+1\) and why that identification is meaningful rather than superficial (hint: it’s the same linear coefficient in both the continuous potential and the discrete map, not merely two unrelated appearances of the digit 3).

Why this milestone replaced the critDim material
This course originally planned to build Weeks 7–8 and 10–12 around a “critDim(n)” formula tied to an external, unverified source (a document referenced only as “Navrátil” in a separate repo). That material has been removed entirely, not merely re-caveated — a repeat of the same lesson 101 taught with \(\pi\)/\(\varphi\)-as-operators and this course’s own \(r^*\) correction: when a claim’s foundation can’t be verified, the right move is removing it, not qualifying it indefinitely. What replaces it (this week, and Weeks 10–12) is grounded entirely in material this course can actually check: the criticality bridge derived above, and a real, honestly-scoped open Lean file on Collatz descent, next.
This week’s content is grounded directly in the AXLE Lean sources cited above — no material in this page depends on the external, unverified source removed from earlier drafts of this course.
-- dm³ 102 · Week 08 · Milestone III — Theorem C.1 by hand
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-- Part 1: reproduce the c*=3 derivation without reference material.
-- Part 2: one paragraph — what "Collatz has c=3" precisely means.
--
-- Submit: your derivation + paragraph.
example : True := trivial