Our task is to derive a lexicon Lex that quantifies the emotional valence of words (from the tweets in D) to emotion classes.
the lexicon may be thought of as a 2d-associative array where Lex[w][c] indicates the emotional valence of the word w to the emotion class c. When there is no ambiguity, we will use Lex(i, j) to refer to the emotional valence of word w i to the emotion class C j .