Case assignment, for and the two to's

The <assign-comp> feature is used to represent the requirements of particular types of clauses for particular complementizers. So while the <comp> feature represents constraints originating from the VP dominating the clause, the <assign-comp> feature represents constraints originating from the highest VP in the clause. <assign-comp> is used to control the the appearance of subjects in infinitival clauses (see discussion of ECM constructions in 8.6.1), to block bare indicative sentential subjects (bare infinitival subjects are allowed), and to block `that-trace' violations. Examples ((33)), ((34)) and ((35)) show that an accusative case subject is obligatory in an infinitive clause if the complementizer for is present. The infinitive clauses in ((32)) is analyzed in the English XTAG grammar as having a PRO subject.

(31)0(31

(32)

Christy wants to pass the exam.  (32)0(32

(33)

Mike wants for her to pass the exam.  (33)0(33

(34)

$\ast$Mike wants for she to pass the exam.  (34)0(34

(35)

$\ast$Christy wants for to pass the exam. 

The for-to construction is particularly illustrative of the difficulties and benefits faced in using a lexicalized grammar. It is commonly accepted that for behaves as a case-assigning complementizer in this construction, assigning accusative case to the `subject' of the clause since the infinitival verb does not assign case to its subject position. However, in our featurized grammar, the absence of a feature licenses anything, so we must have overt null case assigned by infinitives to ensure the correct distribution of PRO subjects. (See section 4.4 for more discussion of case assignment.) This null case assignment clashes with accusative case assignment if we simply add for as a standard complementizer, since NP's (including PRO) are drawn from the lexicon already marked for case. Thus, we must use the <assign-comp> feature to pass information about the verb up to the root of the embedded sentence. To capture these facts, two infinitive to's are posited. One infinitive to has <assign-case>=none which forces a PRO subject, and <assign-comp>=inf_nil which prevents for from adjoining. The other infinitive to has no value at all for <assign-case> and has <assign-comp>=for/ecm, so that it can only occur either with the complementizer for or with ECM constructions. In those instances either for or the ECM verb supplies the <assign-case> value, assigning accusative case to the overt subject.