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Home , Dependency grammar, German grammar, Syntactic hierarchy

Order in German: A Formal Dependency Using a Topological Hierarchy

Kim Gerdes Sylvain Kahane Lattice, Université Paris 7 Lattice, Université Paris 7 75251 Paris Cedex 05 75251 Paris Cedex 05 France France [email protected] [email protected]

pursue this problem any further, but have Abstract limited our description to the link between This paper proposes a description of dependency and topology. Note that it is fun- German word order including phe- damental to our approach that syntactic nomena considered as complex, structure does not include word order. such as , (partial) VP To get the in order, we group them in a fronting and verbal pied piping. Our hierarchy of . The nature and the posi- description relates a syntactic de- tion of these phrases are constrained by our pendency structure directly to a topological model. For instance, a non-finite topological hierarchy without re- can open two kinds of topological sorting to movement or similar phrases, either a , which we call domain, mechanisms.1 with positions for all of its dependents, or a restricted phrase, which forms the verb cluster, with no positions for dependents other than 1 Introduction predicative elements. These two kinds of phrases must be placed in very different The aim of this is to describe the word topological positions. order of German and their comple- The fact that we pass through a (topological) ments. German word order is not free, but phrase structure in order to relate dependency based on fairly simple rules, forming what is and word order distinguishes our approach usually called topological model, which sub- from usual dependency (Mel'cuk & divides the into a hierarchy of topo- Pertsov, 1987; Bröker, 1998; Kahane et al., logical domains that are themselves composed 1998; Duchier & Debusmann, 2001). The of fields (Vorfeld, Mittelfeld, right bracket…) description of German word order closest to (Drach, 1937; Bech, 1955). our analysis is the HPSG grammar of Kathol We start from a syntactic dependency tree, i.e. (1995; see also Reape 1994), who proposes an unordered tree whose nodes are labeled linearization rules exclusively based on a for- with the words of the sentence, and whose malization of the topological structure. How- branches are labeled with syntactic relations ever, as required by the he uses, a among the words (, direct …). regular phrase structure, which we do not need The syntactic dependency structure only en- in our analysis, still underlies the structures codes and modification and obtained. must be completed by the communicative Our work constitutes a syntactic module which structure (partition into theme/rheme, focus…), links (unordered) syntactic structures with which plays a fundamental role in word order. topological phrase structures. Syntactic struc- It permits us to choose among all the different tures are related to semantic structures, possible orders corresponding to a given de- whereas topological phrase structures are re- pendency structure. In this paper we do not lated to phonological structures. In other words, our work lies within the scope of the 1 We would like to thank Werner Abraham, Tilman general framework of Meaning-Text-Theory Becker, Ralph Debusmann, Denys Duchier, and (Mel'cuk 1988), which considers the modeling Stefan Müller for fruitful discussions. Particular of a language as a modular (bi-directional) thanks to Igor Mel'cuk for the inspiration of the correspondence between meaning and text. It particular status we give to the phrase structure. must be clear that, in contrast to X-bar , our topological phrase structure does not rep- resent the syntactic structure of the sentence. 2.2 Topological model Although the dependency information is es- sential in its construction, the phrase structure The internal structure of a domain is a se- only represents topology, i.e. the surface quence of fields. For example, the main do- grouping of the words. Topological phrases main is the underlying pattern of a declarative can be directly related to prosodic groups, and sentence, and it consists of the following se- topology represents an intermediate level be- quence of five fields: [Vorfeld, left bracket, tween dependency and . Mittelfeld, right bracket, Nachfeld]. A domain In Section 2, the results of our findings are resembles a box whose ordered compartments, presented, without recourse to any mathemati- called fields, can themselves accommodate cal formalism, in the usual terminology of new boxes. In addition to the rules listing the traditional German grammars. In Section 3, a fields of each type of box, we propose two mathematical formalism is proposed to state further types of rules: the rules and the grammar fragment described • rules that indicate into which field a word in Section 2. can go–depending on the position of its governor; • 2 Description rules that indicate which type of box a word can create when it is placed into a given field. Word order in German is much freer than in The hierarchy of boxes forms the phrase English. The dependency tree of Fig. 1, which structure we construct. will be our reference example, has a few dozen linearizations: 2.3 Word order rules (1) a. Niemand hat diesem Mann das Buch zu lesen versprochen We have established the following rules for the b. Diesem Mann hat das Buch niemand linear order of verbs and their dependents: zu lesen versprochen • The finite verb takes the second position c. Das Buch zu lesen hat diesem Mann of the main domain, the left bracket. This niemand versprochen verb is also called V2. • A non-finite verb depending on V2 can d. Diesem Mann hat niemand verspro- 2 chen, das Buch zu lesen go into the right bracket. As a result, it e. Diesem Mann hat, das Buch zu lesen, opens a reduced phrase with only one po- niemand versprochen sition for a verbal dependent (see Section f. Zu lesen hat diesem Mann das Buch 2.8 for another possibility). If a subse- niemand versprochen quent third verb joins the verb already in g. Das Buch hat niemand diesem Mann the right bracket, it will again open a versprochen zu lesen phrase with a position to its left, and so on. ‘Nobody promised this man to read the The verbal constituent occupying the right book.’ bracket is called the verb cluster. • Some non-verbal dependents, such as hat ‘has’ separable verbal prefixes (for example the subj aux an of anfangen ‘begin’), predicative ad- versprochen jectives, and governed by a copular ‘promised’ verb or a support verb, can go into the niemand right bracket (the prefix even forms one ‘noboby’-NOM iobj inf zu lesen word with its following governor). In con- diesem Mann ‘to read’ trast to verbs, these elements do not usu- ‘this man’-DAT dobj ally open up a new position for their de- pendents, which consequently have to be placed somewhere else.3 das Buch ‘the book’-ACC 2 We consider that in a compound verb form such as Fig. 1. Dependency tree of the sentences in (1) hat gelesen ‘has read’ the past depends syntactically on the auxiliary, which is the finite verb In this paper, we do not attempt to characterize form (cf. Tesnière 1959, Mel'cuk 1988). The V2 is well-formed German dependency trees al- thus always the root of the syntactic dependency tree. though we recognize that such a characteriza- 3 In examples such as (i), the separable verbal prefix tion is essential if we attempt to describe the an behaves like a subordinated verb intervening be- acceptable sentences of German. tween the ‘main’ verb and its dependent: • One dependent (verbal or non-verbal) of are restrictions that weigh more heavily than any of the verbs of the main domain (V2, the hierarchical position: pronominalization, any verb in the right bracket or even an focus, new information, weight, etc. embedded verb) has to occupy the first position, called the Vorfeld (VF, pre- hat ‘has’ field). • aux All the other non-verbal dependents of the subj versprochen verbs in the domain (V2 or part of the ‘promised’ verbal cluster) can go in the Mittelfeld niemand (MF, middle-field). ‘noboby’ iobj inf • zu lesen Some phrases, in particular sentential ‘to read’ complements (complementizer and rela- diesem Mann ‘to this man’ tive ), prepositional phrases, and dobj even some sufficiently heavy das Buch phrases, can be positioned in a field right ‘the book’ of the right bracket, the Nachfeld (NF, af- ter-field). Like the Mittelfeld, the Nachfeld can accommodate several dependents. Fig. 2. A phrase structure without embedded do- • When a verb is placed in any of the Major mains for (1a,b) Fields (Vor-, Mittel-, Nachfeld), it opens a The fact that a verbal projection (i.e. the verb new embedded domain. and all of its direct and indirect dependents) In the following section we illustrate our rules does not in general form a continuous phrase, with the dependency tree of Fig. 1 and show unlike in English and French, is called scram- how we describe phenomena such as scram- bling (Ross, 1967). This terminology is based bling and (partial) VP fronting. on an erroneous conception of syntax that supposes that word order is always an immedi- 2.4 Non-embedded construction and ate reflection of the syntactic hierarchy (i.e. every projection of a given element forms a “scrambling” phrase) and that any deviation from this con- Let us start with cases without embedding, i.e. stitutes a problem. In fact, it makes little sense where the subordinated verbs versprochen to form a phrase for each verb and its depend- ‘promised’ and zu lesen ‘to read’ will go into ents. On the contrary, all verbs placed in the the right bracket of the main domain (Fig. 2). same domain put their dependents in a com- The constituents which occupy the left and mon pot. In other words, there is no scram- right brackets are represented by shadowed bling in German, or more precisely, there is no ovals. The other three phrases, niemand ‘no- advantage in assuming an operation that de- body’, diesem Mann ‘to this man’, and das rives ‘scrambled’ sentences from ‘non- Buch ‘the book’, are on the same domain scrambled’ ones. level; one of them has to take the Vorfeld, the other two will go into the Mittelfeld. We obtain 2.5 Embedding thus 6 possible orders, among them (1a) and (1b). There are nevertheless some general restrictions on the relative constituent order in hat ‘has’ the Mittelfeld. We do not consider these rules aux here (see for instance Lennerz 1977, Uszkoreit subj versprochen 1987), but we want to insist on the fact that the ‘promised’ niemand inf order of the constituents depends very little on iobj their hierarchical position in the syntactic ‘noboby’ zu lesen structure.4 Even if the order is not free, there diesem Mann ‘to read’ ‘to this man’ dobj das Buch ‘the book’ (i) Er fängt gleich zu schreien an. He begins right_away to shout AN. ‘He begins to shout right away.’ Fig. 3. A phrase structure with an embedded 4 Dutch has the same basic topological structure, but domain for (1a, 1c, 1d, 1e) has lost morphological case except on . For a simplified description of the order in the Dutch Mittelfeld, we have to attach to each complement dependency tree, and linearize them in descending placed in the Mittelfeld its height in the syntactic order. As we have said, when a verb is placed in one emancipated. We have thus four complements of the major fields, it opens an embedded to place in the superior domain, allowing more domain. We represent domains by ovals with a than thirty word orders, among them (1f) and bold outline. In the situation of Fig. 3, where (1g). Among these orders, only those that zu lesen ‘to read’ opens an embedded do- have das Buch or zu lesen in the Vorfeld are main, hat ‘has’ and versprochen ‘promised’ truly acceptable, i.e. those where embedding occupy the left and right bracket of the main and emancipation are communicatively moti- domain and we find three phrases on the same vated by focus on das Buch or zu lesen. level: niemand ‘nobody’, diesem Mann ‘to this man’, and das Buch zu lesen ‘to read the hat ‘has’ book’. The embedded domain can go into the aux Vorfeld (1c), the Nachfeld (1d), or the Mit- subj versprochen telfeld (1a,e). ‘promised’ Note that we obtain the word order (1a) a sec- niemand inf iobj ond time, giving us two phrase structures: ‘noboby’ zu lesen (2) a. [Niemand] [hat] [diesem Mann] [das diesem Mann ‘to read’ Buch zu lesen] [versprochen] ‘to this man’ dobj b. [Niemand] [hat] [diesem Mann] [das das Buch Buch] [zu lesen versprochen] ‘the book’ This structural ambiguity corresponds, we believe, to a semantic ambiguity of communi- Fig. 4. A phrase structure with emancipation for cative type: In (2a), the fact of reading the (1f,g) book is marked (as in Reading the book, no- body promised him that), whereas (2b) is neu- 2.8 Word order in the right bracket tral in this respect (Nobody promised him to German permits different orders inside the read the book). verb cluster. The tense auxiliaries haben Moreover, the structures (2a) and (2b) corre- ‘have’ (past) and werden ‘become/will’ (fu- spond to different prosodies (the left border ture) also allow their dependents to take a of the right bracket is clearly marked with an place on their right in the right bracket accent on the first syllable of the radical). (Oberfeldumstellung or auxiliary flip; Bech, Finally, the existence of this ambiguity is also 1955) (4a). The dependents of this verb go confirmed by the contrast between full infini- again on the left side of their governor, just as tives (with zu) and bare (without zu): in standard order (we thus obtain V V , Bare infinitives cannot form an embedded 1 2 V1V3V2, V1V4V3V2) but it can also join the domain outside of the Vorfeld. Consequently, place to the left of the auxiliary (we thus ob- there are two different prosodies for (3a) (with tain the marginal Zwischenstellung V3V1V2 or without detachment of das Buch ‘the (4c), V V V V ). book’ from zu lesen ‘to read’), whereas only 4 3 1 2 The governed verbs V2 accepting this inverse one prosody without detachment is permitted order form a closed class including the modal for (3b), although (3a) and (3b) have isomor- and perception verbs and some others (helfen, phic dependency trees. Evidence comes also ‘help’, the causative/permissive lassen from the written form recommending a ‘make/let’ … – haben ‘have’ itself also allows comma for (3a) (i.e. preference for the em- this right-placement, which suffices to explain bedded structure), whereas the comma is not the cases of ‘double flip’ as in (4b) giving allowed for (3b). V1V2V4V3). Note that the dependent of haben (3) a. Niemand versucht(,) das Buch zu lesen ‘have’ is the bare . This form, called ‘Nobody tries to read the book.’ the Ersatzinfinitiv, is also possible or even b. Niemand will das Buch lesen preferable for certain verbs when the auxiliary ‘Nobody wants to read the book.’ is in V2 position. (4) a. Er wird das Buch haben lesen können. 2.6 Emancipation He will the book have read can. The dependents of a verb do not have to be in ‘He will have been able to read the book.’ their governor’s domain: They can be ‘eman- b. Ich glaube, dass er das Buch wird ha- cipated’ and end up in a superior domain. For ben lesen können. example, in Fig. 4, the verb zu lesen ‘to read’ I believe that he the book will have read can. has created an embedded domain from which ‘I believe that he will have been able to read its dependent das Buch ‘the book’ has been the book.’ c. Ich glaube, dass er das Buch lesen wird therefore depends directly on the antecedent können. noun and it governs the main verb of the rela- I believe that he the book read will can. tive . As a , it takes its usual ‘I believe that he will be able to read the position in the . book.’ eine Einahmequelle In related languages like Dutch or Swiss- German, which have the same topological rel structure, the standard order in the right "die" bracket is somewhat similar to the German conj Oberfeldumstellung. The resulting order gives rise to cross serial dependencies (Evers 1975, hat Bresnan et al. 1982) Such constructions have subj inf often been studied for their supposed com- verpflichtet plexity. With our subsequent description of die EU inf the Oberfeldumstellung, we obtain a formal dobj structure that applies equally to Dutch. Indeed, zu sich erhalten the two structures have identical descriptions dobj with the exception of the relative order of dependent verbal elements in the right bracket die (keeping in mind that we do not describe the order of the Mittelfeld). Fig. 5. Dependency and phrase structure for (5b) 2.9 Relatives and pied-piping It is now possible to give the word order rules Relative clauses open an embedded domain for relative clauses. The complementizing part with the main verb going into the right of the relative pronoun opens an embedded bracket. The relative pronoun takes the first domain consisting of the complementizer field position of the domain, but it can take other (Kathol 1995), Mittelfeld, right bracket, and elements along (pied-piping) (5). German Nachfeld. The main verb that depends on it differs from English and joins the right bracket. The other rules are in that even verbs can be brought along by the identical to those for other domains, with the relative pronoun (5b). group containing the pronominal part of the (5) a. Der Mann [[von dem] [Maria] [geküsst relative pronoun having to join the other part wird]] liebt sie. of the pronoun in the complementizer field. The man [[by whom] [Maria] [kissed is]] In a sense, the complementizer field acts like loves her. the fusion of the Vorfeld and the left bracket b. Das war eine wichtige Einnahmequel- of the main domain: The complementizing le, [[die zu erhalten] [sich] [die EU] part of the pronoun, being the root of the [verpflichtet hat]]. dependency tree of the relative clause, takes This was an important source_of_income, the left bracket (just like the top node of the [[that to conserve] [itself] [the EU] [com- whole sentence in the main domain), while the mited has]]. pronominal part of the relative pronoun takes ‘This was an important source_of_income, the Vorfeld. The fact that the pronoun is one that the EU obliged itself to conserve.’ word requires the fusion of the two parts and hence of the two fields into one. Note that Before we discuss the topological structure of verbal pied-piping is very easy to explain in relative clauses, we will discuss their syntactic this analysis: It is just an embedding of a verb representation. Following Tesnière (1959) and in the complementizer field. Just like the Vor- numerous analyses that have since corrobo- feld, the complementizer field can be occu- rated his analysis, we assume that the relative pied by a non-verbal phrase or by a verb cre- pronoun plays a double syntactic role: ating an embedded domain. • On one hand, it has a pronominal role in the relative clause where it fills a syntactic position. 3 Formalization • On the other hand, it plays the role of a complementizer allowing a sentence to A grammar in the formalism we introduce in modify a noun. the following will be called a Topological For this reason, we attribute to the relative Dependency Grammar. pronoun a double position: as a complemen- tizer, it is the of the relative clause and it in a lexical field (-). A correspondence rule is 3.1 Definition of the Grammar activated for one of the dependents of the root node, placing it in an accessible field. Just as For a grammar, the parameters to instantiate for the root node, box creation rules are acti- are the vocabulary V, the set of (lexical) cate- vated until the word is assigned to a lexical gories C, the set of syntactic relations R, the set field. This procedure continues until the whole of box B, the set of field names F, the tree is used up. Each time a box creation rule initial field i, the order of permeability of the is triggered, a box is created and a description boxes, which is a partial ordering on B (used rule for this box has to be activated. Finally, for emancipation) and four sets of rules:5 the constraints of the field description rules 1. Box description rules: have to be respected (e.g. a field requiring at least one element can not remain empty). The rule b f1 f2 … fn indicates that the box b consists of the list of fields f1, f2, …, fn. 3.2 Example of a grammar b We will now instantiate our formalism for the f1 f2 … fn German grammar fragment described in sec- tion 2 (leaving aside non-verbal elements in the right bracket) and we will put forward the 2. Field description rules: derivation of (1f) with this grammar (Fig.5). The pair (f,ε) in F×{!,?,+,∗} indicates that the field f has to contain exactly one element (!), V = the German words at most one element (?), at least one element C = { V, AV, EV, Vfin, Vinf, Vbse, Vpp, …, C, (+) or any number of elements (∗). N, X, Y } (V = verb, AV = auxiliary verb, EV = verb 3. Correspondence rules (between the de- with Ersatzinfinitiv, Vfin = finite verb, Vinf pendency and the topological structure): = infinitive with zu, Vbse = base infinitive, The rule (r,c1,c2,f2,b) indicates that a word w2 Vpp = past participle, C = complementizer, of category c2, that exhibits a dependency of X = non-verbal element, Y = anything) ; type r on a word w1 of category c1, can go into field f2 of a box containing w1, if this R = { r } (we consider a unique syntactic rela- box is separated from w1 by borders of type ≤ tion r subsuming all others) b (in other words, the parameter b controls the B = { md, ed, cd, vc, vb, v, xp } emancipation). (md = main domain, ed = embedded do- main, cd = comp domain, vc = verbal r b > cluster, vb = verbal box, v = verb, xp = non-verbal phrase) c1 c2 f2 F = { i, vf, [, mf, ], nf, cf, h, o, u, -} (i = initial field, vf = Vorfeld, ‘[’ = left (In all our figures, boxes are represented by bracket, mf = Mittelfeld, ‘]’ = right ovals, fields by rectangles or sections of an bracket, nf = Nachfeld, cf = comp field, h oval.) = head, o = Oberfeld, u = Unterfeld , - = lexical field, f = vf/mf/nf/cf = major field) 4. Box creation rules: i is the initial field The rule (c,f,b,f’) indicates that a word of category c, placed into a field f, can create a Permeability order box b and go into the field f’ of this box. vb < vc < xp = ed < cd < md Box creation rules are applied recursively until a lexical rule of type (c,f,b,-) is encountered Box description where b is a lexical box with a unique lexical md -> vf [ mf ] nf field, into which the word has to be placed. ed -> mf ] nf Phrase structure derivation starting from a cd -> cf mf ] nf dependency tree vc -> o h u The word labeling the root node of the tree is vb -> o h placed into the initial field i. Box creation v -> - rules are then activated until the word is placed xp -> undescribed Field description 5 We will not present lexical rules indicating each ∗ ∗ lexical entry’s characteristics, in particular its cate- (i,!), (-,!), (vf,!), (cf,!), (mf, ), (nf, ), ([,!), (],?), gory. (h,!), (o,?), (u,?). i [ md + vf [ mf ] nf hat, Vfin: Vfin

i md mf ] ⇒ vf [ nf Vfin

r > ] ] vc vc versprochen, Vpp: + + h + o h u V V V

i ] md vf [ mf vc ⇒ o h u nf Vfin V

ed r > ed ed vc vc f f ] h zu lesen, Vinf: + + ] + vf ] nf + + o h u V Y V V

i ed vf [ mf ] vc vc nf ⇒ mf [ o h u nf Vfin o h u V V

ed ed r ed >r >r das Buch, X: > f f f niemand, X: + + + V Y V Y diesem Mann, X: V Y

i ed vf [ mf ] vc vc nf ⇒ mf [ o h u nf o h u V Vfin X X X V

[zu lesen] [hat] [diesem Mann] [das Buch] [niemand] [versprochen]

Fig. 6. Derivation de (1e)

Correspondence rules Positioning of a non-verbal element in a ma- jor field:8 (r, V, X, f, ed) Positioning of the first verb in the right bracket:6 (r, Y, V, ], -) Box creation rules Creation of the main domain in the initial Positioning of a verb to the left of the pre- field: (Vfin, i, md, [) ceding verb in the right bracket: (r, V, V¬fin, o, vc) Creation of an embedded domain in a major field: (V¬fin, f, ed, ]) Positioning of a verb to the right of the pre- ceding verb in the right bracket:7 Creation of a verbal cluster in the right bracket or the Unterfeld: (V,]/u,vc, h) (r, AV¬inf, EV, u, -)

8 6 This last parameter indicates that it is possible to The last parameter (-) indicates that the right emancipate out of any type of box inferior to ‘ed’ in bracket of a given domain is not accessible when the order of permeability, i.e. ed, xp, vb or vc, but emancipating an element from an embedded domain. not out of cd. Moreover, this rule puts no restric- 7 Auxiliaries with zu do not allow auxiliary flip: tions on the field of the governor. This rule would (i) ∗Er meint das Buch zu haben lesen können. have to be refined to account for NP-internal word He thinks the book to have read can. order phenomena. Creation of a verbal box in the Oberfeld: clusters with more than four verbs are un- (V, o, vb, h) usual). Positioning of a verb: (V, [/h, v, -) References Creation of a non-verbal phrase: (X, f, xp, ?) Creation of a domain for a relative clause:9 Bech Gunnar, 1955, Studien über das deutsche ("C", f, cd, "cf") Verbum infinitum, 2nd edition 1983, Linguisti- sche Arbeiten 139, Niemeyer, Tübingen. 4 Conclusion Bresnan Joan, Ronald M. Kaplan, Stanley Peters, Annie Zaenen, 1982, “Cross-serial Dependencies We have shown how to obtain all acceptable in Dutch”, Linguistic Inquiry 13(4): 613-635. linear orders for German sentences starting Bröker Norbert, 1998, “Separating Surface Order and from a syntactic dependency tree. To do that Syntactic Relations in a Dependency Grammars”, we have introduced a new formalism which COLING-ACL’98, 174-180. constructs phrase structures. These structures differ from X-bar phrase structures in at least Drach, Erich, Grundgedanken der deutschen Satzleh- two respects: First, we do not use the phrase re, Diesterweg, Frankfurt, 1937. structure to represent the syntactic structure of Duchier Denys, Ralph Debusmann, 2001, the sentence, but only for linearization, i.e. as “Topological Dependency Trees: A Constraint- an intermediate step between the syntactic and Based Account of Linear Precedence”, ACL 2001. the phonological levels. Secondly, the nature of the phrase opened by a lexical element Evers Arnoldus, 1975, The transformational cycle depends not only on the syntactic position of in Dutch and German. PhD thesis, University of this element, but also on its position in the Utrecht. topological structure (e.g. the different be- haviors of a verb in the right bracket vs. in a Kahane Sylvain, Alexis Nasr, Owen Rambow, 1998, major field). “Pseudo-Projectivity: a Polynomially Parsable We have to investigate further in various di- Non-Projective Dependency Grammar”, COLING- rections: From a linguistic point of view, the ACL’98, Montreal, 646-52. natural continuation of our study is to find Kathol Andreas, 1995, Linearization-based German out how the communicative structure (which Syntax, PhD thesis, Ohio State University. completes the dependency tree) restricts us to certain word orders and prosodies and how to Lenerz Jürgen, 1977, Zur Abfolge nominaler Satz- incorporate this into our linearization rules. It glieder im Deutschen, TBL Verlag Günter Narr, would also be interesting to attempt to de- Tübingen. scribe other languages in this formalism, con- Hudson Richard, 2000, “Discontinuity”, in S. Ka- figurational languages such as English or hane (ed.), Dependency Grammars, T.A.L., 41(1): French, as well as languages such as Russian 15-56, Hermès, Paris. where the surface order is mainly determined by the communicative structure. However, Mel'cuk Igor, 1988, Dependency Syntax: Theory and German is an especially interesting case be- Practice, SUNY Press, New York. cause surface order depends strongly on both Mel'cuk Igor, Nicolas Pertsov, 1987, Surface syntax the syntactic position (e.g. finite verb in V2 or of English – A Formal Model within the Mean- Vfinal position) and the communicative ing-Text Framework, Benjamins, Amsterdam. structure (e.g. content of the Vorfeld). From a computational point of view, we are Müller Stefan, 1999, Deutsche Syntax deklarativ: interested in the complexity of our formalism. Head-Driven für das It is possible to obtain a polynomial parser Deutsche, Linguistische Arbeiten 394; Niemeyer: provided that we limit the number of nodes Tübingen. simultaneously involved in non-projective configurations (see Kahane et al. 1998 for Reape M., 1994, “Domain Union and Word Order similar techniques). Such limitations seem Variation in German”, in J. Nerbonne et al. reasonable for (e.g. verb (eds.), German in Head-Driven Phrase Structure Grammar, CSLI Lecture Notes 46, Stanford. Tesnière Lucien, 1959, Eléments de syntaxe structu- 9 The quotation marks indicate that the complemen- rale, Kliencksieck, Paris. tizing part of the relative pronoun is not a real word, and hence it does not actually occupy the comple- Uszkoreit Hans, 1987, Word Order and Constituent mentizer field, and must consequently accommodate Structure in German, CSLI Lecture Notes 8, another element. Stanford, CA.