Chapter 2 provides an argument for modeling stress typology in HS by showing that the serial model correctly rules out stress patterns that display non-local interactions, while a parallel OT model with the same constraints and representations fails to make such a distinction.

Chapter 3 discusses two types of primary stress---autonomous and parasitic---and argues that limited parallelism in the assignment of primary stress is warranted by a consideration of attested typology. Stress systems in which the primary stress appears to behave autonomously from secondary stresses require that primary stress assignment be simultaneous with a foot's construction. As a result, a provision to allow primary stress to be reassigned during a derivation is necessary to account for a class of stress systems in which primary stress is parasitic on secondary stresses.

Chapter 4 takes up two issues in the definition of constraints on primary stress, including a discussion of how primary stress alignment should be formulated and the identification of vacuous satisfaction as a cause of problematic typological predictions. It is proposed that all primary stress constraints be redefined according to non-vacuous schemata, which eliminate the problematic predictions when implemented within HS.

Finally, chapter 5 considers the role of representational assumptions in typological predictions with comparisons between HS and parallel OT. The primary conclusion of this chapter is that constituent representations (i.e., feet) are necessary in HS to account for rhythmic stress patterns in a typologically restrictive way.

It is argued that a sensitivity to collective commitments in a conversation is necessary for understanding certain aspects of modal strength, in particular the traditional distinction between strong and weak necessity modals (exhibited by must and ought to in English). It is proposed that strong necessity modals can only reference priorities that are presupposed to be collectively committed to, whereas weak necessity modals are evaluated with respect to a mixed bag of priorities, crucially including ones that are presupposed not to be collectively committed to. A domain restriction approach to weak necessity is adopted, following a demonstration that it is superior to a number of probabilistic alternatives.

Modal verbs and adjectives that take both infinitival and nominal complements are shown to pattern alike across languages in requiring a teleological, or goal-oriented interpretation when their complements are not infinitives (but rather noun phrases or certain Complementizer Phrases). This limitation is lifted with infinitival complements, showing that transitive configurations of certain intensional verbs are not semantically equivalent to the infinitival configurations of the same verbs.

A result of this research is a fine grained analysis of the differences between closely related necessity modals and attitude verbs.

The first configuration arises in restrictions on clitic combinations where v can AGREE with an indirect object and a direct object one at a time (Anagnostopoulou 2003, 2005b, Béjar and Rezác 2003). These configurations give rise to a form of competition: the sec- ond argument will fail to AGREE in any features that it shares with the first. I show that this form of competition extends from restrictions involving local person arguments, where it has been used so far, to restrictions involving third person and plural, which have so far been treated as morphological. Whereas the restrictions on local person lead to ungrammaticality, those on third person and plural result in impoverished morphological realization. I argue that this difference indicates a different role of AGREE for local person vs. third person and plural. Recent work as shown that local person has special syntactic licensing needs (e.g. Béjar and Rezác 2003, Baker 2008, Preminger 2011b). Third person and plural on the other hand, I argue, are syntactically wellformed on their own, but require AGREE to be visible to lexical insertion at PF. Failure to AGREE will lead to absence of morphological realization or ungrammaticality as a function of the features involved. Once restrictions on third person arguments are treated as syntactic, much of the variation across languages in their morphological realization follows from differences in the PF-inventory.

The second situation, two probes AGREEING with the same goal, arises in agreement with objects in Hindi-Urdu. The second part of the dissertation discusses two asymmetries in agreement of T with subjects and objects in conjunction structures. While T-agreement with objects shows sensitivity to linear order (i.a. closest conjunct agreement), T-agreement with subjects does not. I argue that the differences follow from the activity of the goal at the time of agreement. While subjects are syntactically active at the time T probes them, objects are not, because they have already been assigned case by v. As a consequence, the syntactic relation between T and an object cannot value the T's probe in the syntax. Non- syntactic effects like the relevance of linear order affect agreement exactly when valuation cannot be achieved in the syntax.

Both case studies lead to the proposal that syntactically wellformed derivations can be ruled out at PF by failure of lexical insertion. This can happen in two ways. The discus- sion of restrictions on clitic combinations will lead to the conclusion that some languages allow the syntax to generate wellformed structures that contain nodes with so few features that PF cannot insert an exponent for them. The discussion of agreement in Hindi-Urdu will lead to the proposal that the grammar can generate feature bundles with inconsistent features that cannot be spelled out in one form. Overall, PF does both less and more than is often assumed. The restrictions on third person and plural discussed in the first part are traditionally considered to be the result of morphological operations that change the feature content of clitics (Bonet 1991, 1993, 1995, Grimshaw 1997, Noyer 1997). The proposal here reduces the role of PF in these restrictions to spelling out syntactic structures that have reduced feature content as the result of syntactic interactions. Similarly, the proposal about Hindi-Urdu tightly delimits the space where non-syntactic effects on agreement arise. At the same time, PF can rule out syntactically wellformed structures, which is not typically assumed to be possible.

The empirical investigation results in four major findings: First, SR is introduced by its own head, instead of being parasitic to T or C. Second, switch-reference can track Austinian topic situations. Third, it must track topic situations when it is found with coordination, and it cannot do so with intensional embedded clauses. Finally, generalizations or theories based solely on the syntax are not able to account for these facts.

These findings are explained by analyzing switch-reference as a pronominal head in the extended verbal projection of the embedded clause. This head introduces a relation of identity or non-identity between two arguments. One of these is in the dominant clause, the other is the highest indexed constituent in the sister of the SR head. The arguments are selected indirectly, through binding structures that are interpreted as lambda-abstraction. The clausemate argument is bound by the SR head; the properties of feature valuation derive the height constraint. The pronoun introduced by the SR head is bound by the connective. Binding by the connective results in the interpretation of the SR-marked clause as a property. This property is then ascribed to an argument in the dominant clause. This theory accounts for the generalizations, and makes fruitful predictions about other aspects of switch-reference, notably when it tracks non-referential subjects.

This dissertation improves our understanding of switch-reference, of situation semantics, and of reference-tracking in general. It ties reference-tracking to contextual restriction by use of topic situations, which are anaphoric pronouns used to restrict sentential interpretation. It provides the first solid evidence of morphology sensitive to situations. In addition, the theory of switch-reference proposed here relies on independently-motivated mechanisms in the grammar. This reliance links switch-reference to other mechanisms of co-reference from inside an embedded clause, and finds a solid place for switch-reference in linguistic theory.