13. The method of claim 11 , wherein determining the update u utilizes a line-search technique.
11. The method of claim 3 , wherein determining an update for each of the feature weights in the selected update set includes determining an update u for a feature weight (f,l) using a derivation of the formula: u ( f , l ) = arg ⁢ ⁢ min u ′ ⁢ ⁢ l ⁡ ( w + u ′ ⁢ b ( f , l ) ) ; wherein l is a loss function; w is a classifier model; and b is a vector having a value of 1 at coordinate (f,l) and a value of 0 at all other coordinates.