 Compactly supported cohomology

ID: compactly-supported-cohomology

Codex  0 Created 2026-09-24 Updated 2026-09-24

Compactly supported cohomology is the cohomology of cochains vanishing outside a compact subset. Equivalently,

H_{c}^{*} (X) ≅ lim_{K \subseteq X compact} H^{*} (X, X ∖ K) .

 New to topics? Read the docs here!