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Table 2 Feature templates used in the CRF tagger

From: Accelerating the annotation of sparse named entities by dynamic sentence selection

Word Unigram

w i , wi-1, wi+1

&y i

POS Unigram

p i , pi-1, pi+1

&y i

Prefix, Suffix

prefixes of w i

&y i

 

suffixes of w i

&y i

 

(up to length 3)

 

Normalized Word

N(w i )

&y i

Word Shape

S(w i )

&y i

Tag Bi-gram

true

&yi-1y i