Inmathematics, thestructure theorem for Gaussian measures shows that theabstract Wiener space construction is essentially the only way to obtain astrictly positiveGaussian measure on aseparableBanach space. It was proved in the 1970s byKallianpur–Satô–Stefan andDudley–Feldman–le Cam.
There is the earlier result due to H. Satô (1969)[1] which proves that "any Gaussian measure on a separable Banach space is an abstract Wiener measure in the sense of L. Gross". The result by Dudley et al. generalizes this result to the setting of Gaussian measures on a generaltopological vector space.
Letγ be a strictly positive Gaussian measure on a separable Banach space (E, || ||). Then there exists aseparable Hilbert space (H, ⟨ , ⟩) and a mapi : H → E such thati : H → E is an abstract Wiener space withγ = i∗(γH), whereγH is thecanonical Gaussiancylinder set measure onH.