The default tagset that this employs is much more coarse-grained than the Penn tagset. For example, it has only two verb tags, whereas Penn has separate tags fo

The default tagset that this employs is much more coarse-grained than the Penn tagset. For example, it has only two verb tags, whereas Penn has separate tags for infinitives, gerunds, past forms, etc. On the other hand, it supports the peculiar kinds of lexemes that abound in tweets, having separate tags for hashtags, @-mentions, URLs, emoticons, etc. Twitterese English is very different from standard English, and by taking the dedicated-tagset approach that embraces this fact, the authors were able to accurately attribute structure even to text that appears gibberish at first sight. To me, this is very impressive.