Agreement

agr is a complex feature. It can have as its subfeatures:
agr 3rdsing, possible values: +/-
agr num, possible values: plur,sing
agr pers, possible values: 1,2,3
agr gen, possible values: masc,fem,neut These features are used to ensure agreement between a verb and its subject. Where does it occur:
Nouns comes specified from the lexicon with their agr features. e.g. books is agr 3rdsing: -, agr num: plur, and agr pers: 3. Only pronouns use the <gen> (gender) feature. The agr features of a noun are transmitted up the NP tree by the following equation:
NP.b:agr N.t:agr Agreement between a verb and its subject is mediated by the following feature equations:

(562)0(562

(563)

NP_subj:agr VP.t:agr 

(563)0(563

(564)

VP.b:agr V.t:agr 

Agreement has to be done as a two step process because whether the verb agrees with the subject or not depends upon whether some auxiliary verb adjoins in and upon what the agr specification of the verb is. Verbs also come specified from the lexicon with their agr features, e.g. the agr features of the verb sings are agr 3rdsing: +, agr num: sing, and agr pers: 3; Non-finite forms of the verb sing e.g. singing do not come with an agr feature specification.