Agreement

$\langle$agr$\rangle$ is a complex feature. It can have as its subfeatures:
$\langle$agr 3rdsing$\rangle$, possible values: +/-
$\langle$agr num$\rangle$, possible values: plur,sing
$\langle$agr pers$\rangle$, possible values: 1,2,3
$\langle$agr gen$\rangle$, 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 $\langle$agr$\rangle$ features. e.g. books is $\langle$agr 3rdsing$\rangle$: -, $\langle$agr num$\rangle$: plur, and $\langle$agr pers$\rangle$: 3. Only pronouns use the <gen> (gender) feature. The $\langle$agr$\rangle$ features of a noun are transmitted up the NP tree by the following equation:
NP.b:$\langle$agr$\rangle =$ N.t:$\langle$agr$\rangle$ Agreement between a verb and its subject is mediated by the following feature equations:

(508)0(508

(509)

NP_subj:$\langle$agr$\rangle =$ VP.t:$\langle$agr$\rangle$ 

(509)0(509

(510)

VP.b:$\langle$agr$\rangle =$ V.t:$\langle$agr$\rangle$ 

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 $\langle$agr$\rangle$ specification of the verb is. Verbs also come specified from the lexicon with their $\langle$agr$\rangle$ features, e.g. the $\langle$agr$\rangle$ features of the verb sings are $\langle$agr 3rdsing$\rangle$: +, $\langle$agr num$\rangle$: sing, and $\langle$agr pers$\rangle$: 3; Non-finite forms of the verb sing e.g. singing do not come with an $\langle$agr$\rangle$ feature specification.