Decomposition Theorems

Let X $ {\mathcal{X}} $ https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781351056823/5c92c9a4-ddd5-4d42-82bc-8e5903ddaaca/content/inline-math8_1.tif"/> be a σ‐algebra on a set X. A function λ $ \lambda $ https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781351056823/5c92c9a4-ddd5-4d42-82bc-8e5903ddaaca/content/inline-math8_2.tif"/> : X → R $ {\mathcal{X}} \to {\mathbb{R}} $ https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781351056823/5c92c9a4-ddd5-4d42-82bc-8e5903ddaaca/content/inline-math8_3.tif"/> is called a signed measure if