Analytic Morphology – Merging the Paradigmatic and Syntagmatic Perspective in a Treebank Vladimír Petkevicˇ Alexandr Rosen Hana Skoumalová Premyslˇ Vítovec Charles University in Prague, Faculty of Arts [email protected] [email protected] Abstract (often even phonological word); (ii) AVFs may be expressed by a potentially discontinuous string We present an account of analytic verb of a content verb and multiple auxiliaries, some- forms in a treebank of Czech texts. Ac- times in an order determined by information struc- cording to the Czech linguistic tradition, ture rather than by rules of morphology or syntax description of periphrastic constructions is proper; (iii) some auxiliary forms share properties a task for morphology. On the other hand, with some content words – like weak pronouns, their components cannot be analyzed sep- the past tense auxiliary is a 2nd position clitic. arately from syntax. We show how the Our claim is that the two views are compati- paradigmatic and syntagmatic views can ble, complementary and amenable to formaliza- be represented within a single framework. tion within a single framework, combining the traditional paradigmatic view with a syntagmatic 1 Introduction view. This reconciliatory effort is part of a more Analytic verb forms (henceforth AVFs) consist of general goal: a choice of different interpretations one or more auxiliaries and a content verb. The of annotated corpus data, depending on the prefer- auxiliaries can be seen either as marking the con- ences of a user or an application. tent verb with morphological categories or as be- AVFs are assigned a syntactic structure: the (fi- ing part of a multi-word expression, to which the nite) auxiliary is treated as the surface head, gov- categories are assigned. This is the perspective erning the rest of the form – the deep head.2 taken by all standard grammar books of Czech, In Czech, AVFs are used to express the verbal which treat AVFs as a morphological rather than categories of mood, tense and voice in periphrastic a syntactic phenomenon. AVFs are listed in con- passive (all moods and tenses), in periphrastic fu- jugation paradigms quite like synthetic forms for a ture, in 1st and 2nd person past tense, in pluper- good reason: from a meaning-based view, whether fect and in present and past conditional. In all a certain category in a certain language happens to these forms the auxiliary is být ‘to be’. Here we be expressed by a single word or a string of words focus on past tense and conditional forms, includ- is an epiphenomenon. ing pluperfect and past conditional, but the solu- From a different perspective, each of the com- tion works for all the above AVFs, and covers also ponents has its role in satisfying a syntactic gram- negation of some components of the AVFs by the maticality constraint and in making a contribution prefix ne- and can be extended to some other kinds to the lexical, grammatical or semantic meaning of function words, such as prepositions and con- of the whole. This approach is common in both junctions. In (1)–(4) below we show some prop- corpus and generative linguistics (including the- erties of the past and conditional forms. The fi- 1 ories such as LFG or HPSG), where each form nite auxiliary is marked for person, number and is treated as a syntactic word and AVFs belong to mood, while the l-participle3 is marked for gender the domain of syntax. As a result, morphological and number. Past tense (1) consists of the aux- categories are not assigned to units spanning word iliary in the present tense and the l-participle of boundaries. This is for several reasons: (i) an AVF does not emerge as a single orthographical word 2We use the term government in the sense of “subcatego- rization” or “imposition of valency requirements.” 1See, e.g., Webelhuth (1995), Dalrymple (1999), Pollard 3We avoid the frequently used term past participle be- and Sag (1994). cause the same form is also used in present conditional. 9 Proceedings of the 5th Workshop on Balto-Slavic Natural Language Processing, pages 9–16, Hissar, Bulgaria, 10–11 September 2015. the content verb. Present conditional (2) consists and Karlík (2004), who analyze past tense and pe- of the conditional auxiliary and the content verb’s riphrastic passive within the Minimalist Program. l-participle. Past conditional (3) includes an addi- A non-transformational account was pursued by tional l-participle of the auxiliary. In (4) we show Karel Oliva in an HPSG-inspired prototype gram- that other words can be inserted, the auxiliary mar checker of Czech (Avgustinova et al., 1995). l-participle can be repeated, and any l-participle HPSG and LFG have been used to account for sim- can be negated. ilar phenomena in closely related Polish, where the border between morphology and syntax is even (1) Já jsem pˇrišel less apparent than in Czech: all forms of the past I be.PRS.1SG come.PTCP.M.SG tense and conditional auxiliaries are floating suf- ‘I have come.’ fixes, attached either directly to the l-participle, (2) Já bych pˇrišel or to some other preceding word. In the follow- I be.COND.1SG come.PTCP.M.SG ing, we briefly review several proposals for Polish, ‘I would come.’ with an extension to Czech. Based on the analysis of similar phenomena (3) Já bych byl pˇrišel in West European languages, Borsley (1999) pro- I be.COND.1SG be.PTCP.M.SG come.PTCP.M.SG poses two structures for modelling Polish AVFs: ‘I would have come.’ (i) classic VP complementation where the auxil- (4) Kdybys tenkrát nebyl iary is a subject-raising verb selecting a phrasal If-be.COND.2SG back then be.PTCP.M.SG.NEG complement headed by an l-participle (Fig. 1), býval tak duchapˇrítomnˇe and (ii) flat structures where the auxiliary subcat- be.PTCP.M.SG.ITER so readily egorizes for an l-participle and its complements 6 zasáhl... (Fig. 2). The former is used for future tense while intervene.PTCP.M.SG the latter for present conditional and past tense. ‘If you haven’t intervened so readily back This distinction is motivated by the ability or in- then...’ ability of the auxiliary to be preceded by the asso- ciated l-participle and its complements: while the We exemplify the solution using a treebank of future auxiliary allows for VP-preposing, the other 4 Czech. The framework is based on the HPSG. auxiliaries are prohibitive in this respect. The annotation, originally produced by a stochas- tic dependency parser, is checked by a formal VP grammar, using a valency lexicon and imple- Aux VP mented in Trale.5 Trees complying with grammat- ical and lexical constraints are augmented with in- Figure 1: VP complementation. formation derived from the lexicon and any anno- tation provided by a stochastic parser. VP 2 Previous Work Aux VCC... Grammars of Czech take a paradigmatic perspec- tive, treating AVFs as an exclusively morphologi- Figure 2: Flat structure. cal phenomenon (Karlík et al., 1995; Cvrcekˇ et al., 2010; Komárek et al., 1986), glossed over without Kups´c´ (2000) follows Borsley (1999) but rejects describing their syntagmatic and word-order prop- the flat structure for past tense and present con- erties. In Komárek et al. (1986), components of ditional as it makes incorrect predictions with re- AVFs are assigned a particular grammatical mean- spect to clitic climbing. Instead, she assumes VP ing (person, number, tense, mood, voice) but their complementation for all AVFs. syntactic status is not specified. Kups´c´ and Tseng (2005) argue against the uni- The syntagmatic approach has been introduced fied treatment of AVFs. Only the future tense aux- to Czech by Veselovská (2003) and Veselovská iliary behaves like a full syntactic word. In con- 4See, e.g., Pollard and Sag (1994). trast, the forms of conditional auxiliary, albeit syn- 5See http://www.sfs.uni-tuebingen.de/hpsg/archive/ projects/trale/. For more details see Jelínek et al. (2014). 6Heads are denoted by boxed nodes in the figures. 10 VP SurfHead DeepHead VP+MRK XP bych2 Figure 3: Local agreement marker. SurfHead DeepHead nebyl1 spal3 VP Figure 5: Structure of nebyl bych spal ‘I wouldn’t have slept’. XP+MRK VP Figure 4: Nonlocal agreement marker. 3 Our Approach 3.1 Two Types of Heads: Surface and Deep tactic words, are clitics and thus subject to spe- In addition to strictly linguistic criteria for an op- cific word order constraints (dependencies on var- timal analysis of AVFs, our choice of the core rep- ious clitic hosts). Past tense is viewed as a sim- resentation format was influenced by the treebank ple tense and the past tense agreement markings design, which should allow for the derivation of are treated as inflectional elements, even if they syntactic structure and categorial labels of vari- are not attached to the l-participle. This analysis ous shapes and flavours to be used in queries, re- builds on (i) an observation that agreement mark- sponses and exported data. Adopting a uniform ings are much more closely bound to the preceding analysis for all AVFs simplifies the task. Each word than conditional clitics, and (ii) the fact that AVF is represented as a syntactic phrase with two there are no agreement markings used in the third constituents: a surface head daughter represent- person. As a result, the l-participle becomes the ing the auxiliary, and a deep head daughter rep- head of the whole structure. In order to ensure that resenting the auxiliary’s VP complement, which the agreement marking appears somewhere in the includes the content verb.7 Multiple auxiliaries structure the head acts as its trigger, carried by an within a single AVF are surface heads within re- agreement marker, either the head itself (Fig.