Linda Linsefors comments on Natural Latents: The Math

[Linda Linsefors]

In standard form, a natural latent is always approximately a deterministic function of $X$. Specifically: $\Lambda \left(X\right)\approx {\prod }_i(x^{\prime }\mapsto P[X_i=x_i^{\prime }|X_{\overline{i}}\left]\right)$.

What does the arrow mean in this expression?