EN
Let $(X_i, i=1,2,...)$ be a Gaussian sequence with $X_i ∈ N(0,1)$ for each i and suppose its correlation matrix $R=(ρ_{ij})_{i,j≥ 1}$ is the matrix of some linear operator R:l₂→ l₂. Then for $f_i ∈ L²(μ)$, i=1,2,..., where μ is the standard normal distribution, we estimate the variation of the sum of the Gaussian functionals $f_i(X_i)$, i=1,2,... .