Anti-derivation on differential forms with d^2 = 0; satisfies Leibniz d(omega ^ eta) = d omega ^ eta + (-1)^|omega| omega ^ d eta; defines de Rham cohomology H^*_dR(M).
Anti-derivation on differential forms with d^2 = 0; satisfies Leibniz d(omega ^ eta) = d omega ^ eta + (-1)^|omega| omega ^ d eta; defines de Rham cohomology H^*_dR(M).