Deep topic modeling by multilayer bootstrap network and lasso

It is originally formulated as a hierarchical generative model: a document is generated from a mixture of topics, and a word in the document is generated by first choosing a topic from a document-specific distribution, and then choosing the word from the topic-specific distribution. The main difficulty of topic modeling is the optimization problem, which is NPhard in the worst case due to the intractability of the posterior inference. Existing methods aim to find approximate solutions to the difficult optimization problem, which falls into the framework of matrix factorization. Matrix factorization based topic modeling maps documents into a low-dimensional semantic space by decomposing the documents into a weighted combination of a set of topic distributions: D CW where D (:,d) represents the d -th document which is a column vector over a set of words with a vocabulary size of v, C (:,g) denotes the g -th topic which is a probability mass function over the vocabulary, and W ( g,d) denotes the probability of the g -th topic in the d -th document.