Variational inference lets us tractably optimize a lower bound on the log marginal likelihood, while employing a structured inference network encourages non-trivial structure.
a con-ditional random field (CRF) constituency parser (Finkel et al., 2008;Durrett and Klein, 2015), which makes significant independence assumptions, acts as a guide on the generative model to learn meaningful trees through regularizing the posterior (Ganchev et al., 2010).