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 .
20. apparatus of claim 18 , wherein the term addition logic comprises update logic configured to update at least one P(z|w) parameter.