trace:
this feature is not assigned any value and
is used to co-index moved NPs and their traces which are marked by
.
wh:
possible values are +/-
NPs like
who, what etc. come marked from the lexicon with a value
of + for the feature wh.
Non wh-NPs have - as the value of their wh
feature. Note that wh = + NPs are not restricted to occurring in extracted positions, to allow
for the correct treatment of echo questions.
The wh
feature is propagated up by possessives
- e.g. the + wh
feature of the determiner
which in which boy is propagated up to the level of the NP
so that the value of the wh
feature of the
entire NP is +wh.
This process is recursive
e.g. which boy's mother, which boy's mother's sister.
The wh
feature
is also propagated up PPs. Thus the PP to whom has + as the value of its wh
feature.
In trees with extracted NPs, the wh
feature of the
root node S node is equated with the wh
feature
of the extracted NPs.
The wh
feature is used to impose
subcategorizational constraints.
Certain verbs like wonder can
only take interrogative complements, other verbs such as know
can take both interrogative and non-interrogative complements, and yet
other verbs like think can only take non-interrogative
complements (cf. the extracted
and mode
features also play a role in imposing
subcategorizational constraints).
The wh
feature is also used to get the correct
inversion patterns.