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<?xml version="1.0" standalone="yes"?> <Paper uid="E91-1014"> <Title>WHAT SORT OF TREES DO WE SPEAK? A COMPUTATIONAL MODEL OF THE SYNTAX-PROSODY INTERFACE IN TOKYO JAPANESE</Title> <Section position="4" start_page="0" end_page="0" type="metho"> <SectionTitle> A CATEGORIAL UNIFICATION APPROACH TO JAPANESE </SectionTitle> <Paragraph position="0"> I will identify the fundamental unit of Japanese syntax with the traditional category~ bunsetsu (phrase), comprising an open-class &quot;item with - 75 * cliticised closed-class affixes. The open class lexical items are broadly classifiable as nouns and verbs. As described in Whitelock (1987), the closed-class items may be classified in two orthogonal dimensions. First, they form phrases with items of a certain category. Second, they indicate that such a phrase stands in some syntactic relationship (e.g. subject, modifier) to another phrase with a certain category. Thus the phrases of the language fall into the following four categories: nominal - adverbial, e.g.</Paragraph> <Paragraph position="1"> keiko ni (Keiko-DAT), genki ni (healthily) nominal - adnominal keiko no (Keiko-GEN), g~nki na (healthy) verbal - adverbial waratte (laugh-and), amaku (sweetly) verbal - adnominal warau (that laughs), amakatta (that was sweet) The bunsetsu generally behaves as a prosodic unit. Although the syntactic structure of a phrase like (1) is generally taken to be as in (la), its prosodic structure must be as in (lb).</Paragraph> <Paragraph position="2"> (i) Naoko no ant no Naoko's brother 's (la) \[\[\[Naoko no\] ant\] no\] (ib) \[\[Naoko no\] \[ant no\]\] Proposals to handle such 'bracketing paradoxes' have been made within the framework of extended Categorial Grammar (e.g. Moortgat, 1989). We will assume a Categorial Unification Grammar (CUG) (Uszkoreit (1986), Kartunnen (1987)). Whereas an extended CG might capture the polymorphism of a bunsetsu by the derivation step of type-raising, in CUG it may be represented simultaneously by the use of multiple features in the complex categories. Syntactic bracketings such as that shown in (la) are never assigned.</Paragraph> <Paragraph position="3"> Each complex category or sign includes a set of self features, plus the sign-valued features argument and result, which together with a direction constitute a function. The relevant structure of a typical sign, for the bunsetsu keiko hi, is shown in (2).</Paragraph> <Paragraph position="4"> (2) self:\[l\]cat:n function:arg: \[2\]self:cat:s dir:right res: \[2\]self:iobj:\[l\] This sign says 'if a functor is looking for me, it probably needs to know I'm a noun. But 1 am also a function from a sentence of which I am the indirect object into itself'. Note the assumption that well-formedness of the functional representations (i.e. those which include subj, obj etc.) is independently characterised (cf. Coherence and Completeness in LFG (Kaplan and Bresnan, 1982)). This leads to a massive simplification in the combinatorial syntax. Karttunen (1987) proposes a similar treatment for Finnish. Furthermore, I treat free verb forms as S, an approach motivated by the zero-pronominal property of Japanese (see Whitelock 1991 for further details). Also note, contra other work in extended CG (e.g. Barry and Pickering (1990)), that this formulation identifies the function in a combination with the dependent in a functional dependency representation, and the argument with the head.</Paragraph> <Paragraph position="5"> The syntactic rules define three ways of building signs. (3) shows rule A (essentially function</Paragraph> <Paragraph position="7"> The backward version of this rule (L) is the rule of morphological combination. Unlike a syntactic functor, a morphological functor, i.e. an affix, will typically have quite distinct values of <function arg> and <function result>.</Paragraph> <Paragraph position="8"> The chaining rule (C) in (4) constructs the * mother sign with self features from the functor sign * rather than the result sign.</Paragraph> <Paragraph position="9"> (4) M --) D,H (C)</Paragraph> <Paragraph position="11"> Finally, the merging rule (M) in (5) combines two functors looking for the same argument:</Paragraph> <Paragraph position="13"> Though the details are specific to Japanese, it is possible to develop rules of these types for other</Paragraph> <Section position="1" start_page="0" end_page="0" type="sub_section"> <SectionTitle> 76 - </SectionTitle> <Paragraph position="0"> languages. Like an extended CG, but unlike the Lambek calculus, CUG is not structurally complete (i.e. not every substring may be given an analysis).</Paragraph> <Paragraph position="1"> Merging and chaining both correspond approximately to composition in extended CG.</Paragraph> <Paragraph position="2"> However, the CUG formulation brings out the essential difference between them. A constituent built by chaining represents a head lacking a dependent, while merging combines dependents lacking a head. Their effect on derivation depends on the headedness of the language concerned. The main effects are summarised in Fig. 1 (where <=> denotes truth equivalence).</Paragraph> <Paragraph position="3"> left-branching right-branching language language Fig. 1 Derivationa! Equivalence The important aspects of this model are as follows. First, all structures are directly generated by the grammar. The <=> is not a rule for deriving one structure from another. Secondly, the branching structure may be sensitive tO constraints other than semantic ones. In particular, applicatively right-branching structures may be given alternative, psychologically more plausible, analyses. Such analyses are useful in modelling intonation phenomena such as the prosodic bracketing of English phrases like (6) (generated using the English Chain rule), whose applicative bracketing is given in In Fig 3a, the division of the utterance into minor phrases (~t) (P&B's accentual phrase) is highlighted. A minor phrase shows exactly one pitch peak; in this utterance, the minor phrases correspond exactly to bunsetsu. In the section on minor phrasing below, we will look more closely at the relationship between the two.</Paragraph> <Paragraph position="4"> * H H* k so re wa u ma i no mi m* nL~ Fig. 3b Tones and Accent Fig. 3b draws attention to the distinction in shape between the first and the latter two minor phrases. The steep drop in pitch from ma to i in umai, and from mi to m* in nomimono, represents the pitch accent proper. The presence and location of a pitch accent is a lexical property, and its shape is fixed. In contrast, the gentle fall covering 'the rewa of sorewa is a result of sore's lexical specification as unaccented. In such cases, a lower pitch peak than the accented one is realised early in-the minor phrase. In fact, in minor phrases with a late accent, this early peak is also distinguishable, so this &quot;phrasal' tone can be assumed present in all minor phrases. Note the phonetic justification of this prosodic category as the domain of high tone</Paragraph> <Paragraph position="6"> The diagram is annotated according to the notation of Pierrehumbert (1980). The pitch accent is represented as a sequence of tones, here H+L, with the tone that is aligned with the text marked *, hence H*+L. The L tone of the accent is aligned with respect to this. The phrasal H tone and the boundary L tones, L%, are also shown. P&B clearly demonstrate that their sparse tone model, built from pitch accents, phrasal H tones and boundary L tones, is superior to the standard Autosegmental account (e.g. Haraguchi, 1977), where each mora has a fully specified tone. Their careful phonetic experiments show that pitch is a simple interpolation between certain critical points.</Paragraph> <Paragraph position="7"> In this paper, the alignment of tones will not be considered. In English, the repertoire of pitch accents leads to phrases with a variety of tunes, including alignment contrasts such as that between H+L* and H*+L. But in Japanese, the tunes are restricted to the ones in (8).</Paragraph> <Paragraph position="9"> I have bracketed the boundary tones at both ends to indicate that they belong to both preceding and following phrases - they are ambiphrasal. More exactly, I treat a boundary tone between two minor phrases as a property of the major phrase which dominates both of them, though I don't discuss Ltone scaling in the paper.</Paragraph> <Paragraph position="10"> In fig. 3c, the overall downward slope of the pitch trace is picked out. Such a slope, about 10Hz/sec, is often cited as an intonational universal and linked to physiological properties of the speech system.</Paragraph> <Paragraph position="11"> Experiments demonstrate that the second of two equal tones is typically perceived as higher. This phonetic property, declination, must be clearly distinguished from the phonological property downstep or catathesis, as also illustrated in fig. 3c. The pitch difference between the accent H tones of the last two phrases is significantly greater than can be accounted for by declination alone.</Paragraph> <Paragraph position="12"> Several authors (Poser, 1987, P&B, Kubozono) have demonstrated that this effect occurs precisely because an accent lowers all tones in a subsequent phrase. P&B quantify the fact of downstep with a speaker specific constant c, (,, 0.5, in a pitch range normalised to 1). In effect, a tone in a phrase following an accented phrase is c times the height it would be following an unaccented phrase. The prosodic category major phrase is justified phonetically as the domain of downstep; the precise character of major phrases is a point at issue in this paper.</Paragraph> <Paragraph position="13"> so re wa u ma i no mi me no Fig. 3d Schematic Pitch Trace Fig. 3d shows a schematisation of the same pitch contour, correcting for declination and connecting adjacent peaks and troughs with straight line segments.</Paragraph> <Paragraph position="14"> ordered finimsetofprosodic categories: Each local tree in a prosodic representation is licensed by a phrase structure rule of the form Hi &quot;-~ Hi-l&quot;, for i E 1 .. n. Thus a category of one type dominates all and only the categories of one other type, and prosodic trees are fixed in depth and n-ary branching.</Paragraph> <Paragraph position="15"> Acceding to Selkirk and Tateishi (S&T, 1989) the syntax-prosody mapping is then defined by associating with each II b i E 0 .. n, a parameter pair of the form: < edge, xbar>, edge E {left,right}, bar E BAR, i.e. {lex, max, ...} - 78 The parameter settings entail that a prosodic boundary between constituents of category H i must coincide with the edge of a syntactic constituent of category X bar . Note by SLH that a prosodic boundary between Hi must also be a boundary between Flj, for all j < i.</Paragraph> </Section> </Section> <Section position="5" start_page="0" end_page="0" type="metho"> <SectionTitle> MINOR PHRASING </SectionTitle> <Paragraph position="0"> For S&T, the edge parameter for Japanese prosodic categories is uniformly set to left. The X bar value associated with the major phrase ((~) is X max.</Paragraph> <Paragraph position="1"> Therefore, a major phrase boundary must appear at the left edge of any maximal projection.</Paragraph> <Paragraph position="2"> It is not easy to give such a straightforward account of minor phrasing. Under certain circumstances, a sequence Of two bunsetsu may be realised as a single minor phrase. For S&T bunsetsu is never a syntactic category, but rather appears as the prosodic category word (0)). It is the prosodic word rather than the minor phrase which has the parameter setting, in this case X lex. So an upcoming lexical item must initiate a prosodic word, but may or may not initiate a minor phrase. The analysis is summarised in fig. 4. One slight methodological problem is that the prosodic word has no phonetic justification.</Paragraph> <Paragraph position="3"> In the alternative analysis pursued here, two boolean-valued features major and minor are used to prosodically classify syntactic constituents. A single constituent may not be both <minor +> and <major +>, though it may be neither. Each of these feature specifications is associated with characteristic phonetic equations. A constituent labelled <minor +> will contribute a constraint that relates the pitch of the H tones to the value of a register. A constituent labelled <major +> will contribute two sets of constraints - over the relative values of its daughter's registers, and on the pitch of the intermediate L% tones. These constraints are discussed below.</Paragraph> <Paragraph position="4"> The admissible prosodic labellings are defined as those which extend the following prosodic rules. in (9) (+(~), the mother is constrained to be a major phrase, while in (10) (-4~), the mother is constrained not to be a major phrase, though it may or may not be a minor phrase.</Paragraph> <Paragraph position="5"> Note how the category major phrase is recursive (or compound, in the sense of Ladd (1990)), while minor phrase is a single layer.</Paragraph> <Paragraph position="6"> The syntax-prosody interface (SPI) is defined as a subset of <prosodic rules X syntactic rules>. For instance, the optionality of minor phrase formation follows from the inclusion of <+~),A> and <-4~,A> in S&T assume that a minor phrase boundary may never appear within a bunsetsu (PS0). However, Kubozono shows that such phrasings can occur, when the phrase contains both an accented lexical item and a particle with its own accent, such as - 79 made, 'up to'. The SLH cannot license structures as in fig. 5. In the theory assumed here, this data is simply described by the inclusion in SPI of <+(~,L> as well as <-~,L>.</Paragraph> </Section> <Section position="6" start_page="0" end_page="0" type="metho"> <SectionTitle> TONE SCALING </SectionTitle> <Paragraph position="0"> Two-element phrases: When two minor phrases are combined, the accentedness of the first element provides the strongest constraints on the form of the second - if the first element is accented, the second element is downstepped. In addition, an accented element is higher than an unaccented one (this is true of previous L% tones as well as H tones). We associate with the prosodic rule +(~ a scaling equation as in (11): normalised to speaker range, and f is multiplication, this treatment is very similar to P&Bs. I assume the feature <Right downstep> takes the values d n (n > 0), where n is the number of downstepping tones in Left and d is the speaker specific constant (<1) that determines the quantitative aspects of downstep.</Paragraph> <Paragraph position="1"> For each constituent Phrase labelled <minor +>, a set of equations as in (12) is added to the constraint pool: This continues to follow P&B (with g = multiplication) and u (<1) a speaker constant representing the ratio of phrasal to accent high. Three-element phrases: Kubozono considers three element phrases and contrasts the intonation of those with right and left branching applicative structures. For instance, fig. 6 contrasts the two cases in (13), in which all elements are accented. The difference between the second peaks in the two structures is significant at < 1%, the difference between the third at <.1%.</Paragraph> <Paragraph position="2"> (13a) ao'i o'okina me'ron (right branching) blue big melon (13b) ao'i re'monno nio'i (left branching) blue melon smell Fig. 6 Three-element Phrases To describe this, I assign a metrical labelling to a derivation. I assume that contra English, the primary phonetic exponent of such labelling in Japanese is pitch, that is, the H tones in stronger constituents are higher. The labelling associated with the A (and C) rule is as follows: In a structure of the form: \[A X Y\] or \[C X Y\] Y is strong iff it branches This gives the following labellings for the trees in fig. 6.</Paragraph> <Paragraph position="3"> a) \[W IS S WI\] b) \[Is S W\] W\] Labelling rules may of course be overridden by discourse factors. Space precludes a detailed description of prominence projection, that is, the correlation of metrical labelling with discrete terminal grid values. Note that the standard Liberman and Prince convention equates the grid values of the last element in the two cases, in conflict with the data. One formulation would assume a feature, say prominence, which takes the values 1 or p (>1) as a constituent is labelled W or S. Downstepping and prominence interact, with the formulation in (14) replacing that given in (11) above: Note that the register of a constituent is that of its left daughter. If the entire phrase is given the register value 1, and f is multi-plication, the high tones in fig. 6 receive the following pitch values. Right-branching case</Paragraph> <Paragraph position="5"> These figures capture the fact that both second and third elements in the right-branching structure ~re boosted with respect to their left-branching counterparts.</Paragraph> <Paragraph position="6"> S&T's data shows the same effect as that of Kubozono in fig. 6. Their analysis is schematised in fig. 7. The difference between the two cases follows from the binary opposition downstep/no downstep.</Paragraph> <Paragraph position="7"> However, this analysis is no longer supported by Selkirk (p.c.), following Kubozono's clear demonstration that downstep does apply in right-branching phrases. If the first element of a right branching phrase is unaccented, the second element is even higher.</Paragraph> <Paragraph position="9"> Four-element phrases: When we turn to four-element phrases, we find further evidence for i~ecursively structured prosodic domains. Fig. 8 summarises Kubozono's data. All trees represent applicative structures. In structures 1 and 2, the first two elements are a dependent and its head, indisputibly a constituent. In structures 3 and 4, the first two elements are dependents of the same head.</Paragraph> <Paragraph position="10"> This is a non-standard constituent built by the Merge rule. Syntactically, such a constituent appears in coordinate sentence constructions with &quot;gapped' pre-final verbs. Finally, in structure 5, the first two elements do not form a syntactic constituent of any sort, being a head and the dependent of ~iifferent head.</Paragraph> <Paragraph position="11"> These functional equivalence classes correlate closely with the relative heights of the two pitch peaks -- the tighter the connection between the two elements, the lower the second peak. This account compares favourably with other theories that only postulate one such relationship, such as Lambek grammar where every pair of phrases is a ~:onstituent, or those with two, such as phrase8~ructure grammar, or Barry and Pickering's (1990) ve~'sion of Lambek with dependency and non~ependency constituents.</Paragraph> <Paragraph position="12"> However, in principle Barry and Pickering's model could generalise as follows. They characterise any string whose analysis involves abstraction over a function symbol as a non-dependency constituent.</Paragraph> <Paragraph position="13"> But as many further distinctions as the data warrants may be made by considering the number of functors abstracted over. Kubozono's data for four-element phrases supports the case for at least three distinctions (no functor abstraction, one, more than one). Whether further distinctions need to be supported is unclear, as the systematic phonetic exploration of five-element phrases has yet to be carried out.</Paragraph> <Paragraph position="14"> Fig. 8 Four-Element Phrases</Paragraph> </Section> class="xml-element"></Paper>