Natural Transformations When to Use Use this skill when working on natural-transformations problems in category theory. Decision Tree 1. Verify Naturality - eta: F = G is natural transformation between functors F, G: C - D - For each f: A - B in C, diagram commutes: G(f) . eta A = eta B . F(f) - Write Lean 4: 2. Component Analysis - eta A: F(A) - G(A) for each object A - Each component is morphism in target category D - Lean 4: 3. Natural Isomorphism - Each component eta A is isomorphism - Functors F and G are naturally isomorphic - Notation: F ≅ G (NatIso in Mathlib) 4. Functor Category - [C…