1. How to validate this solution🔗

The challenge ships as a list of definitions and theorems left as sorry. A solution must replace every sorry with a real, axiom-free proof of the exact statement asked for — no weakened hypotheses, no renamed goals. Two artifacts let you confirm that:

• The conformance table (first chapter below) restates each of Buzzard's signatures verbatim and discharges it with our declaration. It is checked by lake env lean ChallengeConformance.lean.

• The unit chapters below decompose the proof into self-contained pieces, each linking to its source so you can read the actual argument.

Source repository · verbatim spec · comparator check · unit dependency graph.

Chapters are the 30 units of the decomposition, ordered foundations-first; each unit page is generated from the unit docstring in the repository, so the source of truth stays in code.