Robin corridor

• 2026-08-28 [Conjecture] The Robin corridor is orthogonal to Robin's difficulty, not merely hard: a design of dimension dim is an integer of exactly dim prime factors and level raises the exponents, so the tree varies exponents at fixed prime support, while all of Robin's difficulty lives at growing support omega(n) -> infinity; fixed support is the classical easy half, settled by prod p/(p-1) bounded against a divergent log log, an obstruction read off the definitions. Witness: divisor-avatars.