23. apparatus of claim 18 , wherein the term addition logic does not change either P(z|w) or P(z|d) values for P(z|w) and P(z|d) values in existence prior to the operation of the term addition logic.
18. The apparatus of claim 14 , wherein said trained PLSA model is parameterized by P(z|w) and the term addition logic comprises initialization logic configured to initialize a P(Z|W new ) parameter for each of said at least one new term, wherein the P(z|w new ) parameter is the probability of the latent class z given the new term w new .