The classification therefore reduces to the classification of commuting pairs of antilinear involutions of a complex Lie algebra. The composite "σ"∘"τ" determines a complex symmetric space, while "τ" determines a real form. From this it is easy to construct tables of symmetric spaces for any given formula_38, and furthermore, there is an obvious duality given by exchanging "σ" and "τ". This extends the compact/non-compact duality from the Riemannian case, where either "σ" or "τ" is a Cartan involution, i.e., its fixed point set is a maximal compact subalgebra.