Instead of generating a term by document matrix, where each term is tf • idf (product of term frequency and inverse document frequency), we compute a term by document matrix M D ∈ m×l , where each term in the matrix is the product of the projection of a word onto a target VNC and inverse document frequency.
the term frequency (tf) of a word is replaced by the projection (inner product) of the word onto σ vn (1).