Review.

Lemmatization and Nounification.
Peut-être mieux comme ça : `Finally, lemmatization is applied on nouns (nouns are put in singular form, e.g. \textit{presidents} is mapped to \textit{president}) and nounification on verbs (verbs are transformed into some related noun, e.g. \textit{born} is mapped to \textit{birth}).`