 Cartan formula (algebraic topology)

ID: cartan-formula-algebraic-topology

Codex  0 Created 2026-10-06 Updated 2026-10-14

Sq^{k} (ab) = \sum_{i + j = k} Sq^{i} (a) Sq^{j} (b), P^{k} (ab) = \sum_{i + j = k} P^{i} (a) P^{j} (b) .

It is named after Henri Cartan and is distinct from Cartan's magic formula for the Lie derivative of a differential form, named after Élie Cartan.

 New to topics? Read the docs here!