In HPSG selection is expressed in two ways:
- The ARG-ST (short for ARGUMENT-STRUCTURE) list contains all syntactic arguments of a lexical head.
- ARG-ST list of the verb walk: [ ARG-ST < NP > ]
- ARG-ST list of the verb read: [ ARG-ST < NP, NP > ]
- ARG-ST list of the verb rely: [ ARG-ST < NP, PP[on] > ]
- ARG-ST list of the proper noun Chris: [ ARG-ST < > ]
- ARG-ST list of the singular count noun table: [ ARG-ST < DP > ]
- ARG-ST list of the singular count noun discussion (as in The discussion with the city council about the new train station took forever.):
[ ARG-ST < DP, PP[with], PP[about] > ]
- The VAL (short for VALENCE) feature encodes the grammatical functions that a syntactic category can (still) assign.
The value of the VAL feature is internally structured into the following attributes:
- COMPS (for COMPLEMENTS)
- encodes whether the sign requires complements.
- the COMPS value is a list with possibly more than one element.
- SPR (for SPECIFIER)
- encodes whether the sign requires a specifier.
- the SPR value is a list with at most one element.
- for advanced cases: SUBJ (for SUBJECT)
To handle predicative uses of noun phrases we need to distinguish specifiers from subjects:
Pat is my best friend.
Here my is the specifier of friend and Pat counts as the subject of friend.
- MOD (for MODIFIER)
- encodes whether the sign can modify a head.
- the MOD value is a list with at most one element.
There is a natural relation between the ARG-ST list and the VAL value:
- At the lexical level: The ARG-ST list is the concatenation of the SPR list and the COMPS list (cf. Argument Realization Principle).