Today I tried to write an English rule that matches the sentence 'Its great!' and would be supposed to suggest 'It's' instead of 'Its' for the first token.
The obvious way to do it would be a rule that matches 'Its', followed by an adjective and
SENT_END. But the text analysis shows that in the sentence 'Its great!' the adjective reading is removed from the token 'great' by the disambiguator.
That would be a great feature if we could assume that all sentences are correct, but this is an assumption we must not make in a grammar checker.
Maybe we should add a feature that allows access to the tags that were there before the disambiguation process.
Related post by Michael: [de] Improvement of POS analysis