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With nominal comparatives, we saw that a single analysis was amenable
to both ``pure'' comparatives and elliptical comparatives. This is
not possible for adjectival comparatives, as the following examples
demonstrate:
(430)0(430
- (431)
- The dog is less patient.
(431)0(431
- (432)
- The dog is less patient than the cat.
(432)0(432
- (433)
- The dog is as patient.
(433)0(433
- (434)
- The dog is as patient as the cat.
(434)0(434
- (435)
- The less patient dog waited eagerly for its master.
(435)0(435
- (436)
- *The less patient than the cat dog waited eagerly for its master.
The last example shows that comparative adjectival phrases cannot
distribute quite as freely as comparative nominals.
The analysis of elliptical comparative adjectives follows closely to
that of comparative nominals. We build them up by first adjoining the
comparative element to the A node, which then signals to the AP node,
via the compar feature, that it may allow a than-clause to
adjoin. The relevant trees are given in
Figure 22.8. CARBa is anchored by more, less and as, and axPnx is anchored by both than
and as.
Figure 22.8:
Elliptical adjectival comparative trees
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(a) CARBa tree |
(b) axPnx tree |
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The advantages of this analysis are many. We capture the
distribution exhibited in the examples given in ((431)) - ((436)).
With CARBa, comparative elements may modify adjectives wherever
they occur. However, than clauses for adjectives have a more
restricted distribution which coincides nicely with the distribution
of AP's in the XTAG grammar. Thus, by making them adjoin to AP rather
than A, ill-formed sentences like ((436)) are not allowed.
Figure:
Comparativized adjective triggering CnxPnx.
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There are two further advantages to this analysis. One is that
CARBa interacts with nxPnx to produce sequences like
more exquisite horse than Black Beauty, a result alluded to at
the end of Section 22.3.1. We achieve this by
ensuring that the comparativeness of an adjective is controlled by a
comparative adverb which adjoins to it. A sample derivation is given
in Figure 22.9. The second advantage is that we get
sentences such as ((437)) for free.
(436)0(436
- (437)
- Hobbes is better than Bill.
Since better comes from the lexicon as compar+
and this value is passed up to the AP node, axPnx can adjoin as
desired, giving us the derivation given in
Figure 22.10.
Figure:
Adjunction of axPnx to comparative adjective.
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Notice that the root AP node of Figure 22.10 is compar-, so we are basically saying that strings such as better than Bill are not ``comparative.'' This accords with our use of the
compar feature--a positive value for compar signals that
the clause beneath it is to be compared against something else.
In the case of better than Bill, the comparison has been
fulfilled, so we do not want it to signal for further comparisons. A
nice result which follows is that axPnx cannot adjoin more than
once to any given AP spine, and we have no need for the NA constraint
on the tree's root node. Also, this treatment of the comparativeness
of various strings proves important in getting the coordination of
comparative constructions to work properly.
A note needs to be made about the analysis regarding the interaction
of the equivalence comparative construction as ... as and the
inequivalence comparative construction more/less ... than. In
the grammar, more, less, and as all anchor CARBa, and
both than and as anchor axPnx. Without further
modifications, this of course will give us sentences such as the
following:
(437)0(437
- (438)
- *?Hobbes is as patient than Bill.
(438)0(438
- (439)
- *?Hobbes is more patient as Bill.
Such cases are blocked with the feature equiv: more, less, fewer and than are equiv- while as (in
both adverbial and prepositional uses) is equiv+. The
prepositional trees then require that their P node and the node to
which they are adjoining match for equiv.
An interesting phenomena in which comparisons seem to be paired with
an inappropriate as/than-clause is exhibited in ((440)) and
((441)).
(439)0(439
- (440)
- Hobbes is as patient or more patient than Bill.
(440)0(440
- (441)
- Hobbes is more patient or as patient as Bill.
Though prescriptive grammars disfavor these sentences, these
are perfectly acceptable. We can capture the fact that the as/than-clause shares the equiv value with the latter of the
comparison phrases by passing the equiv value for the second
element to the root of the coordination tree.
Next: Adverbial Comparatives
Up: Propositional Comparatives
Previous: Nominal Comparatives
XTAG Project
1998-09-14