Complex Predicates and Multidimensionality in Grammar (2019)

Abstract: This paper contributes to the on-going discussion of how best to analyze and handle complex predicate formations, commenting in particular on the properties of Hindi N-V complex predicates as set out by Vaidya et al. (2019). I highlight features of existing LFG analyses and focus in particular on the modular architecture of LFG, its attendant multidimensional lexicon and the analytic consequences which follow from this. I point out where the previously existing LFG proposals have been misunderstood as viewed from the lens of theories such as LTAG and HPSG, which assume a very different architectural set-up and provide a comparative discussion of the issues.

## introduction lexical-functional grammar (lfg) is a theory that posits several different types of linguistic representations, each with their own logical structure and vocabulary. this architectural choice reflects the realization that different parts of the grammar are of different mathematical complexity and encode different types of information. within syntax, lfg posits two different types of structure: the c(onstituent)-structure encodes information about constituency, linear order and the hierarchical organization of constituents. the f(unctional)-structure, on the other hand, encodes dependency type of information, for example of a predicate and its arguments, specifiers and modifiers @xcite @xcite . the syntax interacts with further components of grammar, such as the a(rgument)-structure, which encodes predicate-argument relations at the lexical semantic level, or the s(emantic)-structure, which encompasses clausal semantics and must, of course, also itself interact with a-structure. these interactions are accomplished via lfg's mathematically well-defined projection architecture. the multidimensional architecture of lfg predisposes it to be prepared for mismatches across linguistic representations. complex predicates have been demonstrated to involve a challenging mismatch between a(rgument)-structure and syntax and it is thus perhaps no accident that very detailed formal treatments of complex predicates across a range of languages have been formulated especially within lfg @xcite @xcite . these formal treatments also included a clear differentiation of complex predicates from auxiliation and control constructures @xcite . the lfg analysis of complex predicates crucially includes a notion of argument structure composition, by which a complex, bi-or multiclausal a-structure corresponds to a monoclausal f-structure. @xcite , @xcite and @xcite demonstrated that this argument structure composition must be mediated by the syntax as the parts of a complex predicate can be distributed across the clause and do not necessarily have to be adjacent to one another. this stands in contrast to the initial formulation of the relationship between a-structure and f-structure, which saw the mapping from thematic roles to grammatical functions as being accomplished only within the lexicon. once it was established the the mapping between a-structure and f-structure needed to be mediated via the syntax, the theory was extended to allow for this. a crucial but sinple component of the extension was the idea that a-structures can contain variables which are then instantiated by other a-structures in the clause. the composed a-structure is placed into correspondence with grammatical functions at f-structure as a whole. this type of dynamic argument structure composition is difficult to accomplish for frameworks that depend heavily on lexical encoding, like ltag (lexicalized feature-based tree-adjoining grammar), hpsg (head-driven phrase structure grammar) or ccg (combinatory categorial grammar). the essential problem is that they do not have recourse (or have only limited recourse) to structures which can introduce information that is not lexically rooted. a recent contribution by @xcite proposes to meet this challenge for ltag. they do so with respect to the concrete case of hindi noun-verb complex predicates and draw heavily on previous work within lfg and by @xcite . in the process, they discuss features of the existing lfg analyses and compare and contrast the approaches with ltag. this paper picks up on some of their discussions and observations from an lfg perspective. in what follows, i first comment on the properties of hindi n-v complex predicates as set out by @xcite and provide different perspective on the data (section 2). i then highlight features of existing lfg analyses, point out where the previously existing proposals have been misunderstood by @xcite and provide a comparative discussion of the issues (section 3). section 4 concludes the paper. ## properties of complex predicates there are two related properties of complex predicates i would like to draw attention to. one concerns the nature of the relationship between the predicational parts of a complex predicate, the other the productive nature of complex predicates. both points are discussed in @xcite ; however, i believe their significance has not been fully appreciated. ## conclusion in conclusion, @xcite present an elegant and comprehensive analysis of n-v complex predicates for ltag. the analysis involves positing an elementary tree for the nominal, nicely modeling the fact that it is the main predicational element of the clause. the light verb is adjoined as an auxiliary tree and this adjunction is required because the nominal elementary tree has no tense specification and the structure must acquire one. it does this via the light verb. the tree for the light verb also specifies relevant lexical semantic information contributed by the light verb. this contains established information that serves to constrain the combinatory possibilities for complex predication. the analysis is comprehensive in that it takes into account the many different properties of hindi n-v complex predicates that have been adduced over the years, e.g., in terms of scrambling, modification, agreement and lexical semantics. the ltag and lfg analyses are similar in that they use sophisticated feature unification mechanisms for functional information associated with phrase structural nodes. however, they differ sharply in terms of the complexity of overall grammar architecture. lfg is inherently multidimensional, with a complex set of interacting yet distinct levels of representation. one of the components of grammar is a-structure, which is placed into correspondence with f-structure. a-structure is taken to be governed by its own set of constraints. complex predication is accounted for via argument composition and identification and crucially allows for each member of a complex predicate to contribute arguments and further lexical semantic information to the overall joint predication. this stands in contrast to the ltag analysis developed by @xcite , in which only the elementary tree of the nominal contributes arguments to the predication. the tree associated with the light verb is not devoid of semantic content: it encodes the relevant lexical information contributed by the light verb in terms of features that govern the combinatory possibilities within the complex predicate. this entails that several different elementary trees have to be posited for any given noun, in order to anticipate all the possible combinatory possibilities and attendent effects on the overall argument structure. the design decision to concentrate all the information about number and type of arguments on the nominal leads to one of the points raised above, namely, that it is not clear how instances of complex predicate stacking can be dealt with without blowing up the lexicon considerably. overall it seems that analyses within ltag are severely constrained in their analytical choices because of the fundamental design decisions taken in developing tag. they lead to a pleasingly simple and elegant system, but result in a proliferation of stipulative lexical entries due to the combination of the heavy reliance on lexicalization and an absence of a separate representation of argument structure that can operate independently from phrase structural representations. in contrast, lfg assumes a complex multidimensional and interacting architecture of grammar, which includes a separate level of astructure. 2 the advantages of such a complex system of interacting parts are clear: one can produce rich representations of linguistic structure and one has a number of competing analytical possibilties that one can choose among, depending on the precise nature of the data at hand. on the other hand, the disadvantages are also clear. theoretical and computational linguists alike must struggle to understand and model a complex system. in this they receive comparatively less definitive guidance as to their analytical choices -these must be developed on the basis of an understanding and theory of the modular architecture of grammar. phenomena like those of complex predicates provide just the right kind of object of study of interface phenomena, particularly across different theoretical frameworks.