what is $z$ in a generative model is $z a random variable why is z$ a variable? why is the subject assignment for a word a node in the generative model is $theta a random variable in the distributed which direction is the z$ node in the generative model? what is the definition of the $z$ node which is a generative distribution what do the $z$ nodes represent? what is the z$ node in lda which generative model has a random variable z$? what is the term for the topic assignment what is the purpose of the $z$ node what is the node used in the generative model of the dirichlet how many parameters does the generative model have what is the topic assignment for the word what is the node in the generative model what is the generative model lda what does z$ mean in the model which node represents a sampled topic from the topic distribution