, w N ), the embedding feature of w t (for 1 ≤ t ≤ N ) is obtained by projecting it onto a n-dimensional vector space through the look-up table L w ∈ R |w|×n , where |w| is the size of the vocabulary.
their attempt to tackle the third problem by pairing a conditional random field with their feed-forward tagger provided little accuracy improvement and vastly increased computational complexity, incurring a large efficiency penalty.