Such lexicons can be created manually, or automatically from data.
given a lexicon L and a surface word w, we define the following operations: • Stemming -let S w = {s 1 , ..., s l } be the set of possible morphological stems (lemmas) of w according to L. 2 • Inflection -let I w = {i 1 , ..., i m } be the set of surface form words that have the same stem as w. i ∈ I w iff S i S w = ∅.