# About Hierarchical Latent Dirichlet allocation (hLDA)

I am reading Blei et al.'s paper (Hierarchical Topic Models and the Nested Chinese Restaurant Process) about hLDA.

I am confused about the details of deriving the posterior of $p(\boldsymbol c_m| \boldsymbol w, \boldsymbol c_{-\boldsymbol m}, \boldsymbol z)$. What is the exact formula of this posterior? How could I draw $\boldsymbol c_m$ from this posterior?

Sincerely thanks for giving helps.