Given the task definition and input, reply with output. In this task, you are given the abstract of a research paper. Your task is to generate a summary of this abstract. Your summary should not be very short, but it's better if it's not more than 30 words.

In this work we construct flexible joint distributions from low-dimensional conditional semi-implicit distributions. Explicitly defining the structure of the approximation allows to make the variational lower bound tighter, resulting in more accurate inference.
Utilizing the structure of distributions improves semi-implicit variational inference