Phrasal Verbs and the LinGO-ERG

Transcription

1 Phrasal Verbs and the LinGO-ERG Aline Villavicencio Computer Laboratory, University of Cambridge, Ann Copestake Computer Laboratory, University of Cambridge, Abstract In this paper we investigate the phenomenon of phrasal verbs, discussing their characteristics and the challenges that they present for possible treatments. We also discuss the treatment for phrasal verbs in a particular grammar, the LinGO-ERG, and the coverage it provides. Possible ways of extending the coverage of this grammar are analysed and proposed, taking into account the regular patterns found in some productive combinations of verbs and particles. 1 Introduction and Motivation In this document we will look at one of the phenomena of phrasal verbs, analysing the characteristics that make them so interesting and challenging at the same time. According to the definition in Collins Cobuild Dictionary of Phrasal Verbs, the expression phrasal verb refers to the combinations of verbs with adverbial or prepositional particles. As an example, we have the verb make, that can be combined with the particle out, in make out. One of the problems with such verbs is that the meaning of the combination of the verb with the particle cannot always be inferred from the meaning of the verb and the particle, independently. For example, the verb make means: to produce, to cause, to perform, to force, to be or become, to calculate,..., and out means: used to show movement to a place or position that is not inside, among other things. But when combined together in make out they can mean to see, hear or understand (something or someone) with difficulty, as in What I couldn t make out was your motive (from the Cambridge International Dictionary of Phrasal Verbs, page 213). It can also mean to write all the necessary information on (an official form, document, etc.), as in Did you make out a receipt? (also from the Cambridge International Dictionary of Phrasal Verbs, page 214). Apart from the fact that these meanings are not related to the meanings of the individual words used in the combinations, the possibility of a number of alternative meanings for each combination further adds to their complexity. Another source of variation is the position of the particles in relation to the verb and its complements. Some particles have a fixed position in relation to the verb, such as come up, in She came up with the idea, where the particle is expected immediately after the verb, thus the ungrammatical *She came with the idea up. Others have a more flexible order in relation to the verb, and can equally well occur immediately after the verb, or after another complement, such as eat up, in If you eat up all your cereal, I ll give you a piece of chocolate, and in She sat on my bed and made me eat it all up (both from Collins Cobuild Dictionary of Phrasal Verbs, page 95). However, the same flexibility does not apply if the NP object is a pronoun. Then She likes chocolate, so she ate it up is grammatical, but *She likes chocolate, so she ate up it is not. 1

2 In terms of usage, phrasal verbs are sometimes thought of as more informal and not as appropriate for written English, where some consider better to replace them for a single word equivalent. However, it may be the case that the single word equivalent has a different range of use, meaning or collocation and cannot be easily used to replace the phrasal verb, or it may sound too formal or pompous when used. The number of phrasal verbs is constantly growing, with new combinations appearing. However, it is often the case that these new combinations form some productive pattern that can be captured, with the particles using a fixed particular meaning to contribute to the meaning of a number of combinations. This is the case of the particle up, indicating movement or position, and the phrasal verbs rollerskate up, telemark up and skateboard up. Even though some verbs accept flexible orders, and/or optional constituents, there is usually a preference for a particular form, that is the most frequently employed. This kind of information is useful, and some dictionaries like Collins Cobuild Dictionary of Phrasal Verbs contains, for each sense of a phrasal verb, the possible variations, in order of frequency. All these factors make phrasal verbs an interesting phenomenon to investigate, while at the same time being challenging to capture appropriately. In what follows we are going to discuss the treatment given to phrasal verbs by one specific version of the LinGO-ERG, and the coverage that it allows. In section 3 we look at the case of resultative constructions and analyse a possible treatment for them. We finish with some conclusions and a discussion of future work. 2 Phrasal Verbs in the LinGO-ERG As part of the Linguistic Grammars Online (LinGO) initiative, a large-scale grammar for English (the English Resource Grammar or ERG) was built. The LinGO-ERG is based on the HPSG framework, and it is being used as a basis to implement treatments for multiword expressions. In terms of phrasal verbs, the LinGO-ERG lexicon (version of January 2001) contains 295 entries. These entries are classified as belonging to 11 different types, shown in table 1. Table 1: Classes of Idioms Type LinGO Pattern Example Frequency VP1 v np particle le Verb NP Particle - - VP2 v particle le Verb Particle break down 93 VP3 v particle cp le Verb Particle S find out 1 VP4 v particle inf le Verb Particle VP Ò turn out 1 VP5 v particle pp* le Verb Particle (PP) find out 8 VP6 v particle pp le Verb Particle PP look up 5 VP7 v particle prd le Verb Particle PRD turn out 1 VP8 v np prep particle only le Verb NP Particle make over 4 VP9 v particle np le Verb Particle NP & Verb NP Particle blow up 46 VP10 v prep particle np le Verb Particle NP & Verb NP Particle add on 131 VP11 v particle np pp to le Verb NP Particle (PP ØÓ µ point out 5 These groups encode syntactic and semantic variation. In terms of syntactic variation, these types specify which complements the verb takes, and the order in which they appear. In the LinGO-ERG, a phrasal verb can take sentential complements (VP3), infinitival complements (VP4), PP complements (VP5 and VP6), a predicative complement (VP7), NP complements (VP1, VP8, VP9 and VP10), an NP and a PP complements (VP11), and no complement at all (VP2). Phrasal verbs belonging to types VP1 to VP8 and VP11 have fixed order, with the particle always occurring at a certain position. An example is make over in They will make the car over to Helen. Those belonging to classes VP9 and VP10 have flexible orders, such as pick up in Mark picked up the apples and Mark picked the apples 2

3 up,and this is captured by rules that change the order of the NP and Particle in the subcategorisation list. The rule applies to verbs of types VP9 and VP10, and changes them into verbs of type VP1. Other phrasal verbs have optional PPs (VP5), such as find out in He found out and in He found out about the surprise party. This is obtained by having a single category for both cases, where the PP is marked as optional, and a lexical rule that removes the optional PP complement from the subcategorisation list of the category when appropriate. Phrasal verbs are also differentiated in terms of the semantics of the particle. In the grammar, particles and prepositions have a basic type (e.g on rel), which is further specialised according to the semantic contribution of the word. The basic predication type for prepositions and particles is divided into two subtypes, one that has a semantic content (independent rel) and the other that doesn t (selected rel). In this way all particles and prepositions are defined as being of the basic type, but those that have a semantic contribution are further specialised as subtypes of independent rel and the others that don t have are defined as being of selected rel. All the types for phrasal verbs have the particle with selected rel predication. Some particles have the NP object as semantic argument, and others don t. Types VP8, VP10 and VP11 have the object NP as both argument of the verb and of the particle. An example is bring over in They bring over the dog, with (partial) semantics: (1) bring over(e1,x,y)they(x)dog(y)over(e1,y) For all the other verbs with NP objects, the NP is only argument of the verb, and not of the particle. For example They blow up cars has semantics: (2) blow up(e1,x,y)they(x)cars(y)up(e1) These are the types to which all phrasal verbs in the lexicon belong. In addition to getting all the information defined in the types, each entry also specifies the particular verb and particle involved in the combination. This is done through the selection of the semantic predicate of the specific particle, in the feature SYNSEM.LOCAL.KEYS.-COMPKEY of the verb. For example, for a phrasal verb like book up this feature is specified as up rel, as shown in the following entry: book_up_v1 := v_prep_particle_np_le & [ STEM < "book" >, SYNSEM.LOCAL.KEYS [ KEY _book_up_rel, --COMPKEY _up_rel ] ]. In this entry, the verb is specified as book, and the particle as up, of type v prep particle np le. In SYNSEM.LOCAL.KEYS.KEY, which is the standard location for the main predicate, the specific verb-particle relation, book up rel, is defined. The same mechanism is used for verbs that idiosyncratically select particular prepositions in some verb-pp combinations, with the preposition defined in SYNSEM.LOCAL.KEYS. OCOMPKEY (for example to rel for compare to, where to has semantic content and of rel s for remind of, where of has empty semantics). These are the dimensions implemented in the LinGO-ERG, for different types of phrasal verbs. In terms of coverage, if we compare the 295 phrasal verbs in LinGO-ERG with those in the Alvey Tools lexicon, which contains 2906 verb-particle constructions, there are 56 verbs that are in the former and not in the latter, which is a considerable amount given the size of these lexicons. The treatment for phrasal verbs defined in the LinGO-ERG was implemented in a much smaller and simpler grammar, the MWE grammar, to provide the testing grounds for possible extensions to this treatment. By having this much more circumscribed grammar, it is easier to concentrate on the phenomena being investigated without the potential interferences caused by the interaction between constructions in a larger grammar. However, the 3

4 alternatives explored are all made compatible with the LinGO-ERG for a possible transfer to this larger domain. 3 A Treatment for Aspectual and Resultative Constructions When building a lexicon, one would ideally aim at encoding only idiosyncratic information explicitly, with information that is predictable being automatically inferred or generated. In terms of phrasal verbs, there is a range of variation between the predictable and the idiosyncratic combinations. Bolinger [1971] acknowledges that...a large scale gradient between more or less freely composable phrases, through degrees of figurative extension down to more or less tightly bound stereotypes with the steps clearly interrelatable and often systematic and predictable. Recent work on particles [Bame 1999] investigated systematic and predictable relations between various senses of particles, attempting to obtain patterns of verb-particle combinations. In what follows, we discuss a treatment for resultative and aspectual constructions involving the particle up, that is based on the work of Bame [1999]. Among the patterns of verb-particle combinations, one case where the contribution of the meaning of the verb and that of the particle to the meaning of the phrasal verb can be predicted is that of resultative constructions. When a verb is combined with a resultative particle, the resulting meaning is that of a locational or directional state. One example is that of the verb carry and the particle up in sentences 3 and 4: (3) Tom carried the TV, (4) Tom carried up the TV Sentence 3 describes a general carrying event, while sentence 4 describes a carrying event in a particular direction. As a result of the carrying up the NP object, the TV, it is going to be in a higher location, as indicated by its (partial) semantics: (5) carry(e1,x,y)tom(x)tv(y)up(e1,y) Bame extends Wechsler s [1997] analysis of resultative predication to phrasal verbs. Wechsler s analysis uses the fact that verbs denoting events can restrict the arguments denoting their possible result states. Bame proposes that the semantics of the verb be shared with that of the combined particle, and that the latter contains some semantics of its own, that further specifies the semantics of the verb when present. In the case of carry up, carry has semantics specified as: CONTENT RELATION BECOME motion-rel ACT i UND j spatial-rel UND j and up as: CONTENT BECOME direction-rel UND i DIRECTION up-rel PATH k When they are combined in the phrasal verb carry up the semantics is: This could be implemented so that resultative particles have a semantics of their own (e.g. up(e1,y)) and a verb denoting a movement event can occur with the resultative particle up denoting a location or direction, that will further specify the meaning of the verb: 4

5 CONTENT motion-rel RELATION ACT i UND j direction-rel BECOME UND j DIRECTION up-rel PATH k (6) John moved up the books (7) move(e1,x,y)john(x)book(y)up(e1,y) Thus, the particle adds a specific meaning to the meaning of the sentence. This treatment can be implemented in the MWE grammar, by defining a lexical rule that takes a verb belonging to a certain group (e.g. movement verbs), and automatically adding the particle up denoting a location or direction, to the verb s subcategorisation list. Moreover, the particle is defined as adding a semantic contribution, taking the NP object of the verb as its semantic argument. Another case of verb-particle combinations that is productive is that of up as an aspectual particle, where the particle intensifies the event denoted by the verb: (8) He tore the letter (9) He tore up the letter In the second sentence up indicates that the action has been done to completion, and that the letter is now in small pieces. When aspectual up combines with a verb denoting an activity or accomplishment, the particle describes the action of the verb as done to a point of finality, completion, exhaustion, or over-satiation, with the object of the action being fully affected. In relation to the examples 8 and 9, the meaning of the sentences needs to capture that: (10) tear(e1,x,y) he(x) letter(y) (11) tear(e1,x,y) he(x) letter(y) up(e1) fully affected(y) As in the resultative case, the aspectual particle up also brings a particular semantic contribution to the meaning of the sentence, in this case that the object is fully affected. To implement this solution, a lexical rule is defined for adding a particle to the subcategorisation list of a verb. The lexical rule that generates aspectual phrasal verbs can be seen in figure 1, where the input is an aspectual verb (denoting an activity or accomplishment), which is a type in an orthogonal hierarchy specifying classes of verbs. This rule then generates as output the phrasal verb, where a particle was added to the subcategorisation list (COMPS) and the semantics was specified as having a fully affected object. In this way, when the particle is added, it also adds its particular semantics, intensifying the semantics of the verb. This rule applies to words such as brush, which is of type wipe-instrument-trans-verb, a subtype of the aspectual verb type, and generates brush up as shown in figures 2 and 3, respectively, where only the relevant features are shown. As it stands, this rule can be applied to form a phrasal verb from any particle combined with an aspectual verb, only constraining that the particle should have a selected rel semantics. However, a further constraint can be straightforwardly incorporated in the rule by specifying the group of particles that it should apply to, i.e. the subtype of aspectual particles which has as instances particles such as up and out, as shown in figure 4. The idea is to have a whole group of lexical rules for capturing different regular patterns of phrasal verbs. These rules would be organised in an inheritance hierarchy as subtypes of, for instance, phrasal verb lexical rule. In the MWE grammar, the predication types are all implemented as strings, except for particles and prepositions, which have a basic non-string type. Thus, the type pred-type has subtypes string, for regular predications, and real-pred-type, for prepositions and particles. Following the LinGO-ERG treament of particles and preposi- 5

6 aspectual-verb HEAD verb SPR 6 COMPS 13 lexeme HEAD verb SPR 6 COMPS HEAD prep SEM:KEYS:KEY1 selected rel 13 SEM:RELS arg1-2-relation ARG0 12 ARG2 20 arg1-relation PRED fully affected ARG0 12 ARG1 20 Figure 1: Aspectual Phrasal Verb Lexical Rule wipe-instrument-trans-verb HEAD verb COMPS phrase SEM semantics KEYS:KEY1 0 brush rel RELS arg1-2-relation PRED 0 ARG0 index ARG1 index ARG2 index Figure 2: Lexical Entry for brush wipe-instrument-trans-verb HEAD verb COMPS HEAD prep SEM KEYS:KEY1 0 selected rel RELS arg0-relation PRED 0 ARG0 1 phrase SEM semantics KEYS:KEY1 2 brush rel RELS arg1-2-relation PRED 2 ARG0 1 ARG1 index ARG2 3 arg1-relation PRED fully affected ARG0 1 ARG1 3 Figure 3: Lexical Entry for brush up 6

7 aspectual-verb HEAD verb SPR 6 COMPS 13 lexeme HEAD verb SPR 6 aspectual prep COMPS HEAD prep SEM:KEYS:KEY1 selected rel arg1-2-relation SEM:RELS ARG0 12 ARG2 20 arg1-relation PRED fully affected ARG0 12 ARG Figure 4: Aspectual Phrasal Verb Lexical Rule with Constraint tions, the latter type is further specialised according to the semantics of each word, given that there is a distinction between predication types for prepositions and particles that have a semantic content, and types for those that don t have semantic content. Particles and prepositions are defined as being of the base type, but those that have a semantic contribution are further specialised as subtypes of independent rel and the others that don t have are defined as being subtypes of selected rel. For instance, the verb rely idiosyncratically selects for the preposition on, and for this particular combination, the preposition is specified as being a case of selected rel type, representing the resulting meaning of a sentence such as Bill relied on the car: (12) rely on(e,x,y) bill(x) car(y)on s(e1,y) For the case of verb-particle combination, all the particles in LinGO-ERG are defined in the types as having a selected rel type, with no independent contribution. 4 Future Directions In order to further exploit the sub-regularities presented by certain verb-particle combinations, one possibility is to group verbs that follow a certain pattern into a class according to the possible particles they can combine with. For instance, one such class could be that of movement verbs being combined with location or direction particles. Any member of that particular verb group could then be combined, by a lexical rule, with any member of that specific particle group: Movement-verbs: come, go, jump, run, walk,... Location-or-Direction-particles: away, down, in, out, up,... Thus, we could productively generate all the possible verb-particle combinations allowed by these groups: come away, come down, come in, come out, come up, go away, go down,... For each verb group and associated particle group there would be a lexical rule that would generate the combinations, adding the semantics of the particles, as appropriate for each particle group. In the case of the groups exemplified above, the particles have a semantic contribution that further specifies the event denoted by the verb. For instance, walk away in sentence 13 with meaning shown in 14, has the meaning of the particle adding a resulting location to the event specified by the verb: (13)The boy walked away 7

8 (14) walk(e,x) boy(x) away(e,x) However, other particle groups may have the particles bringing different semantic contributions to the event of the verb. But that would be specified in the relevant lexical rule. A first attempt to investigate this possibility proved to be problematic, since dictionaries have a limited number of entries, and do not list exhaustively all the possible verb-particle combinations. In this investigation we attempted to classify verbs into groups, starting with a subset of verbs that denote movement, and the subset of particles that involve location or direction, trying to classify the verbs according to the range of particles they can take. At first, we determined for each particle, the group of verbs that can be combined with it, using the Particles Index of the Collins Cobuild Dictionary of Phrasal Verbs, which is a guide to the way particles are used in English Phrasal Verbs. Then we tried to find a common set of verbs that occurred in each of the particle groups, but there seemed to be only small overlaps between some of the groups. We will still pursue this idea, but first, a more appropriate resource with a large list of verb-particle combinations needs to be found. We are now exploring other possibilities such as the Alvey Tools lexicon, Comlex and CIDE. 5 Conclusions In this document, we analysed the phenomena of verb-particle constructions, starting with a more theoretical perspective, where we characterised phrasal verbs. Such verbs present themselves as an interesting subject, since they follow a certain pattern, but have variation enough (in terms of syntax, semantics, frequency, and so on) to prevent them from being captured in a single account. We also described the treatment given to phrasal verbs in the context of LinGO-ERG, analysing the different types defined, and the range of variation allowed by the grammar. This treatment was replicated in the MWE grammar, that allowed us to concentrate on investigating possible treatments for phrasal verbs, in a much smaller and circumscribed domain, without the complexity of such a large grammar, and without the possibility of interference from other constructions. One of the possibilities implemented was a treatment of aspectual and resultative constructions based on Bame s treatment, as discussed in section 3. It provided the first attempts at encoding the regularities and sub-regularities presented by the combinations of verbs with particles, in these grammars. A second possibility was investigated, with the idea of further exploring the regular patterns found in the combination of verbs with particles, by joining them into groups. But before this idea can be further pursued, we need to find more adequate resources to explore it. In general, phrasal verbs have been proving to be a challenging enough subject to test the range of mechanisms and multiword facilities provided by the LKB system. Acknowledgments Our thanks to Timothy Baldwin and Francis Bond for their comments on this paper. This research was supported in part by the NTT/Stanford Research Collaboration, research project on multiword expressions. 6 References Bame, K. Aspectual and resultative verb-particle constructions with up. Handout of talk given at Ohio State University Graduate Linguistics Student Colloquim, Bolinger D. The Phrasal Verb in English. Cambridge MA: Harvard University Press, Cambridge International Dictionary of Phrasal Verbs. Cambridge University Press, Cambridge International Dictionary of Idioms. Cambridge University Press, Collins Cobuild Dictionary of Phrasal Verbs. Harper Collins Publishers, Wechsler, S. Resultative Predicates and Control. In Texas Linguistic Forum 38: The Syntax and Semantics of Predication. Dept. of Linguistics of the University of Texas at Austin,