- removing geodb phrases
- use Latin-ASCII-simple transliteration (no umlauts, etc.)
- no digit normalization for admin component phrases and postcodes
- tag = START + word, special feature for first word in the sequence
- add the new admin boundary categories
- for hyphenated non-phrase words, add each sub-word
- for rare and unknown words, add ngram features of 3-6 characters with
underscores to indicate beginnings and endings (similar to language
classifier features)
- defines notion of "rare words" (known words with a frequency <= n where
n > the unknown word threshold), so known words can share
statistical strength with artificial and real unknown words
several copies of the same training example will be generated.
1. with only lowercasing
2. with simple Latin-ASCII normalization (no umlauts, only things that
are common to all languages)
3. basic UTF-8 normalizations (accent stripping)
4. language-specific Latin-ASCII transliteration (e.g. ü => ue in German)
This will apply both on the initial passes when building the phrase
gazetteers and during each iteration of training. In this way, only the
most basic normalizations like lowercasing need to be done at runtime
and it's possible to use only minimal normalizations like lowercasing.
May have a small effect on randomization as examples are created in a
deterministic order. However, this should not lead to cycles since the
base examples are shuffled, thus still satisfying the random permutation
requirement of an online/stochastic learning algorithm.
