1: Input: Training examples (xi, yi) 2: α ← 0 3: for t ← 1 .. T do 4: if zi = yi then 7: Collins 2002's perceptron training algorithm were adopted again, to learn a discriminative classifier, mapping from inputs x ∈ X to outputs y ∈ Y .
many theoretically useful features such as higherorder word-or POS-grams can not be utilized efficiently.