Before parsing starts, a preprocessing step is used to first attach the paired punctuations as properties of their neighbouring words, and then remove them from the sentence.
unigram for p in β0, β1, β2, β3, σ0, σ1, σ2 ppunc for p in β0, β1, β2, σ0, σ1 ppunc pw, ppunc pt bigram for p, q in (σ0, β0), (σ0, β1), (σ0, β2), (σ0, σ1), (σ0, σ2) ppunc qpunc, ppunc qt, ppunc qw for p, q in (σ2, σ0), (σ1, σ0), (σ2, σ0) ppunc qt, ppunc pt qt for p, q in (σ2, σ0), (σ1, σ0), (σ0, β0) dpq ppunc pt qt Table 3: Feature templates.