5. The computer controlled method of claim 1 , wherein said trained PLSA model is parameterized by P(z|w) and the step of incrementally adding said at least one new term represented by w new comprises initializing 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 .
5. The computer controlled method of claim 1 , wherein said trained PLSA model is parameterized by P(z|w) and the step of incrementally adding said at least one new term represented by w new comprises initializing 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 . 9. The computer controlled method of claim 5 , wherein the step of incrementally adding comprises updating at least one P(z) parameter.