§§1–3; dimension-three comparison on page 5
Milnor distinguishes topological from smooth classification and explains why the distinctions disappear in dimension three. A homology sphere alone does not satisfy the Poincaré hypothesis.
Passage details
Passage ID: poincare-conjecture:entry:dimension-scope:v1
Source item: §§1–3; dimension-three comparison on page 5
Source record: milnor-poincare-description@clay-description-observed-2026-10-12