In Rota's paper (An Alternierende Verfahren for General Positive Operators), Theorem 2 says that: Let P$P$ be a doubly stochastic operator which is selfadjoint in L2 (S, \Simga, \mu)$L^2 (S, \Sigma, \mu)$. Then there is a dilation of the sequence of operators P^{2n}$P^{2n}$ into a martingale E_n$E_n$.
My question is, what does he mean by a dilation? Is he referring to the definition of dilation: Q$Q$ is a dilation of T$T$ in T^n = EQ^n Dv$T^n = EQ^n D$ where T:V\to V$T:V\to V$, Q:W\to W$Q:W\to W$ and D: V\to W$D: V\to W$?