English. The paper focuses on the relation between Action Types (ontological objects that identifies the referential potential of a verb) and the Thematic Structure and Alternations of verbs. The empirical analysis shows that these linguistic features are not properties of the verb itself, but vary in relation to its referential variation. Given this evidence, we argue that Thematic Structure and Argument Alternation can help in the identification of the different types of action to which a verb refers, providing evidences to define the granularity of action concepts in the development of an ontology of actions.
Action verbs are among the most frequent words
in ordinary communication, and their correct
processing constitutes an underpinning element for a
wide series of human-machine interaction tasks.
The formalization of action verb meanings has
often been linked to propositional representations
within decompositional approaches
Nevertheless, even if these semantic components are usually assumed to reflect the general structure
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permitted under Creative Commons License Attribution 4.0
International (CC BY 4.0).
of action conceptualization, the linguistic and the
cognitive levels of categorization are not
equivalent and should not be confused
For instance, the verb to push can refer to actions in which the force causes the movement of the object in space (e.g. in a sentence like John pushes the basket under the table), as well as to actions in which the object does not move (e.g. John pushes the fabric into a ball). This differential property is more than enough to cognitively distinguish these events in different action concepts. As a consequence, the need for a cognitive level of action categorization which is independent from the lexical one becomes clear.
In this paper, we investigate the role of one type of linguistic information, specifically Thematic Structure and Argument Alternations, in the definition of action types, i.e. types of action concepts that gather together single datapoint in the IMAGACT ontology of actions. We point out that Thematic Structure is not a property of the verb itself, since different structures may be present for the same verb. Our aim is to show how these features are linked to action types and how this correlation can be useful for the definition and the induction of Action Types1.
In section 2, we show the innovative
methodology assumed by the IMAGACT Ontology of
Action for representing the meaning of action verbs,
focusing on their referential properties rather than
on their intensional definition. In sections 3 and
4, we will see through a case study that the
induction of the referential variation of verbs can take
advantage of linguistic features. Thematic
Struc1Similarly, previous work in Word Sense Disambiguation
In the IMAGACT multilingual Ontology of
Actions2
The scenes linked to a verb have been then grouped in broader categories called Action Types5 (hereafter also ATs or Types). ATs are defined as higher level concepts which fall in the semantic variation of a verb, useful to represent its referential potential in a more compact way, reducing an excessive granularity in the representation of meaning6. ATs have been created exploiting similarity judgments among scenes and considering Local Equivalent verbs, i.e. all the verbs
3Only in their basic, physical meaning, so excluding all metaphorical and phraseological uses.
4Besides English and Italian, the list of fully mapped language comprenends: Arab, Chinese, Danish, German, Hindi, Japanese, Polish, Portuguese, Serbian, Spanish, Greek.
5See, for instance, Table 1 which represents the main variation of the action verb to close.
6As a matter of fact, some verbs in IMAGACT can be
linked to several dozen scenes, and the most general ones,
like to take and to put, are linked to about 100 scenes.
that could co-extend to the same scene
Thematic structure and syntactic frame
information of verbs are usually provided by most
lexical resources, such as VerbNet
In this section, we show that Thematic Structure (TS) is not a property of the verb and we will verify: 1) to what extent it can be considered a property of the action types in the variation of a verb; 2) to what extent it can provide a differential feature for the identification of ATs. We consider as TS the minimal themathic structure7 which is necessary to interpret a verb as an instance of a specific AT.
There are cases in which the TS is the same all through the verb variation. Frequently, one specific thematic structure is associated to activity verbs that show almost no variation in their meaning. This is the case of the verb to drink, who has only one AT. The verb to close, on the contrary, shows a significant variation in the IMAGACT ontology (7 ATs, four of them represented in table 1), but all types present the same TS (AG-V-TH). In these cases, thematic structure cannot play any role in the definition of different types, which are 7The set of roles used in IMAGACT is based mainly on the set used in VerbNet. identified on the basis of ontological features of the theme (e.g. a body part vs an artifact) or by the kind of result produced (spatial consequences vs functional consequences), and even by the set of equivalent verbs which provide a differential property of each ATs (to shut vs. to lock vs. to close up vs. to clench).
Verbs like to close shows that TS is not a necessary differential of ATs, but, as the next examples will point out, it can help to select among the interpretations of a general verb. This is the case with verbs like to press and to push which record different TSs possibilities across their variation. Let’s consider the verb to press. In the IMAGACT ontology it shows 10 different ATs. We can observe groups of Types that share the same TS. Types a (table 2) and b (table 3) present AgentVerb-Theme-Destination structure. In both cases, the destination is necessary to represent the event type, which cannot be identified otherwise. In type a, the Agent compacts the Theme into a block, changing its shape but not its volume. In type b the Agent squeezes the Theme, reducing its volume.
John presses the scraps into a block AG-V-TH-DEST to push, to compact
Types c, d and e (tab.4, 5, 6) differ from types a and b since Destination is not necessary and AGV-TH is sufficient to identify the action.
Despite the common Thematic Structure, they clearly identify different actions for cognitive reasons. In type c the Theme is a humans body part, and the concept implies a compression as an intersubjective activity, whereas in type d the Theme is an object and the compression implies a functional correlation. In type e the Theme undergoes a continuous scalar pressure, not limited to a single impulse.
Although these TS commonalities among types show that TS is not necessarily predictive of a single type, TS helps in the distinction of action types. For example, TS restricts the range of possible interpretation of a general verb like to press in the case of type a and type b (table 2 and 3) versus type c, d and e (tables 4, 5 and 6). The distinction between these groups of types (which is independently motivated) is mirrored by the different TSs.
TS may constitute an important feature for the definition of granularity of action types in the verb variation. Type c (the doctor presses the shoulder, tab.4) and type f (the thief presses the gun into Marys back, tab.7) are distinguished in reason of their TS: they are similar actions from a cognitive point of view and they can be paraphrased both with to push, but the TS of the verb in the two events is different.
The thief presses the gun into Mary’s back AG-V-TH-DEST to push
Two cases in the variation of to press are characterized by a specific TS: type g (AG-V-THINSTR) and type h (AG-V-TH-RESULT). Type g (tab. 8) necessarily requires the instrument in its minimal structure, contrary to all other types; type h (tab. 9) requires the expression of the result of the action. TS is predictive of the Action Type in those cases.
Considering the variation of a verb like to press8, we can conclude that TS is not peculiar of the verb but is related to its types. Given the cases in which one TS is shared by multiple types, it is clear that types distinction is not a function of the thematic variation (which is actually related to the intersection of multiple features). However, TS has a role in type prediction, since it helps identifying the features of a type. 4
Argument Alternations (AAs) are one of those
properties of the verb that have received great
attention in a large body of literature after Levin
(1993). As we will see, also AAs are not
properties of the whole verb, but rather characterizes the
verb in its types. Considering the verb to press, it
8Further similar examples have been extracted from the
IMAGACT ontology; however, for space limitations, we
refer only to the cases already discussed.
has been previously stated that it shows the
conative alternation, i.e. “a transitivity alternation in
which the objects of the verb in the transitive
variant turns up in the intransitive conative variant
as the object of the preposition in a prepositional
phrase headed by the preposition at (sometimes on
with certain verb of ingesting and the push/pull
verbs)”
Type c: The doctor presses the shoulder ! The doctor presses on the shoulder Type d: John presses the button ! John presses on the button Type e: John presses the pedal ! John presses on the pedal Other types result in agrammatical sentences when the conative alternation is applied:
Type a: *John presses at/on the scraps into a block Type g: *The tailor presses at/on the cloth with the iron
Considering now to push, a verb that shares many interpretations with to press, only some types of to push (types a, b, c, d but not e, f and g) allow this alternation:
Type a: John pushes the button ! John pushes on the button Type b: John pushes the shoulder ! John pushes on the shoulder Type c: John pushes the lever ! John pushes on the lever Type d: John pushes the pedal ! John pushes on the pedal Type e: Mary pushes the chair ! *Mary pushes on the chair Type f : Mary pushes the toothpaste ! *Mary pushes on the toothpaste Type g: Mary pushes the fabric ! *Mary pushes on the fabric
In addition to the conative alternations, other two alternations can be seen in the variation of the verbs considered: the resultative construction and the theme-instrument alternation. The resultative construction presents a phrase that describes the state achieved by the referent of a noun phrase as a result of the action. As noted already by Levin (1993, p. 100), it cannot be predicated in case of oblique: a. The silversmith pounded the metal flat. b. *The silversmith pounded on the metal flat.
This alternation is found only in type h for to press:
John presses the can ! John presses the can flat
Lastly, we find an alternation between the Theme and the Instrument, not listed in Levin (1993). In this case, the Instrument from sentence 2b (which can be seen as the result of a conative alternation) becomes the Theme in sentence 2c. (1) (2) Type f : the thief presses the gun into Marys back ! the thief presses Marys back with the gun9 For the verb to push, only types i and d allow it: Type i: The thief pushes the gun into Marys back ! The thief pushes Marys back with the gun Type d: John pushes the pedal ! John pushes the foot on the pedal
As a whole, if considered together, TS and AA can reduce the underdetermination of types. In other words, when two types share the same TS, they can be predicted from a difference in their argument alternations. This is the case, for example, for types a (table 2) and f (table 7) of to press, which share the TS AG-V-TH-DEST, but differ with respect to the theme-instrument alteration: only type f allows it, not type a.
In the variation of to push, types e and a share the same TS (AG-V-TH) but type e does not allow the conative alternation (6=Mary pushes on the chair), contrary to types a (John pushes on the button). 5
In this paper we have investigated the relation between Thematic Structure and Action Types. The empirical analysis reveals that Thematic Structure and Argument Alternations are not properties of the whole verb, but rather of the verb in its Types. We have provided evidence about the saliency of both Thematic Structure and Argument Alternations in the identification of Action Types. Although TS and AA do not determine the variation of a verb across different ATs, these linguistic features can, indeed, reveal characterizing features of a Type, helping us in the disambiguation of concepts and in the recognition of the necessary level of granularity in building our ontologies.
9Other types do not allow the theme-instrument alternation: *John presses the hand on the scraps (type a); *Mary presses the hand on the clothes (type i). For completeness, we report some examples of to push for which this alternation does not hold: *Mary pushes on the chair with her hand (type e); *Mary pushes the hand on the box (type h).
The doctor pushes his hand on the shoulder
This alternation can be considered as a particular case of locative alternation. In terms of Levin (1993), the noun shoulder would represent the location argument, whereas hand would be considered the locatum. Also in this case, the themeinstrument alternation does not apply to all types of the variation of to press, but rather characterizes specific types.
Type g: the tailor presses the clothes with the iron ! The tailor presses the iron on the clothes Type c: the doctor presses the shoulder ! the doctor presses the shoulder with the hand ! the doctor presses the hand on the shoulder Type d: John presses the button ! John presses the button with the hand ! John presses the hand on the button