A σ-additive set function μ : ℳ → ℝ (allowing at most one infinite value). Hahn decomposition ⇒ μ = μ^+ − μ^− uniquely; Jordan decomposition gives total variation |μ|.
A σ-additive set function μ : ℳ → ℝ (allowing at most one infinite value). Hahn decomposition ⇒ μ = μ^+ − μ^− uniquely; Jordan decomposition gives total variation |μ|.