Lifting generic points

Abstract: Let $(X,T)$ and $(Y,S)$ be two topological dynamical systems, where $(X,T)$ has the weak specification property. Let $\xi$ be an invariant measure on the product system $(X\times Y, T\times S)$ with marginals $\mu$ on $X$ and $\nu$ on $Y$, with $\mu$ ergodic. Let $y\in Y$ be quasi-generic for $\nu$. Then there exists a point $x\in X$ generic for $\mu$ such that the pair $(x,y)$ is quasi-generic for $\xi$. This is a generalization of a similar theorem by T.\ Kamae, in which $(X,T)$ and $(Y,S)$ are full shifts on finite alphabets.