By David Schueler, Computational Linguist
Semantic Role Labeler Argument Categories
As I discuss in this article, we recently decided to undergo some major revisions to the corpora we use to train some of our NLP tools. Specifically, we applied major corrections to the corpora for part-of-speech tagging and for dependency parsing; for the latter, see also this article.
For our semantic role labeler, we did a less aggressive revision of the data. Our concern here was more the viability of the set of categories available to label predicate/argument relations, hereafter called “argument types”, rather than the accuracy and consistency of the labeled data per se. To that end, we eliminated some of the argument types present in the original annotated corpus, whose categories correspond roughly to those given in Bonial et al. 2010.
The predicate/argument pairs that were labeled with those labels we eliminated were re-labeled to other existing labels. In a few cases this was done by hand, by inspecting individual sentences to see which new label made the most sense. In most other cases, they were automatically re-labeled based on their original label, via a merger rule, such that all predicate/argument pairs originally labeled with argument type X will now be re-labeled to argument type Y.
From this process, we arrived at a new reduced set of argument types. We then revised the names we give to those remaining types, to better reflect the semantic range that they cover. Since some of the argument types absorbed data from predicate/argument pairs originally labeled differently, the semantic range for some of the types expanded, requiring a different name for the type.
Therefore, in this article, I give an exhaustive list of the currently supported argument types which result from this revision. I give the name of each type, a brief description, which may include a few different semantic criteria, and one or more examples which exemplify some of those criteria.
In the example sentences, the predicate is italicized, while the argument is given in boldface. The sentences are given as tokenized strings.
Argument type: Agent/Experiencer
Description: This type applies either to the party responsible for some event (1), or who is the primary recipient of a psychological experience directly described by the predicate (2).
(1) People send me emails all of the time .
(2) Outdoors , they can also personally experience wetland ecology .
Argument type: Patient/Theme/Affected
Description: This type applies typically to the entity which is affected by the event, often ((3), (4)) but not always (5) undergoing a change of state. It also applies to the first argument of the verb ‘be’ (6).
(3) People send me emails all of the time .
(4) He also said investment by businesses is falling off .
(5) Tom Mintier has details .
(6) Well that ’s a deal .
Argument type: Beneficiary/Goal/Predicate/Comitative
Description: This type applies to a few different partially related cases. It can apply to the entity that benefits from the event (7), or to the entity which receives something as a result of the event (7), or to the second argument of the verb ‘be’ (8), or to an entity that accompanies some other participant in the event (9).
(7) People send me emails all of the time .
(8) Well that ’s a deal .
(9) So he went in to stay with them .
Argument type: Destination/EndingPoint/Source
Description: This type applies to phrases that indicate motion toward (10) or away from (11) as part of the event described by the predicate. Sometimes the motion is metaphorical ((12), (13)).
(10) the first night we went over to the Inner Harbor
(11) These figures come to us from Abu Dhabi television .
(12) Some estimates have gone as high as 80,000 members .
(13) They will break them to pieces like clay pots .
Argument type: Location
Description: This type applies to phrases that indicate the place at which the event takes place (14), without motion to or from that place implied. This category can also apply to a metaphorical location (15).
(14) Outdoors , they can also personally experience wetland ecology .
(15) There ’s nothing to report on that front .
Argument type: Speaker/Addressee/Conjunction/Interjection
Description: This type contains several subcases, but generally applies to phrases which do not apply to the event introduced by the predicate directly, but serve some separate function in the conversation, such as to designate who is speaking (16), indicate the addressee of the sentence (17), relate the sentence to the rest of the conversation as with conjunctions (18) or discourse-related adverbs (19), or interject with an utterance that somehow relates the speaker’s feeling or other orientation toward the sentence that they are saying ((20), (21)).
(16) Jim : I like the graphic ,
(17) is that what it is Alex ?
(18) But they allowed me to drive on .
(19) He also said investment by businesses is falling off .
(20) Well that ’s a deal .
(21) oh they do not remember your brother .
Argument type: Manner/Means/Extent
Description: This type applies to phrases which indicate various aspects of the event, such as the manner in which the event took place (22), the means by which it happened (23), or the extent to which it occurred (24).
(22) Outdoors , they can also personally experience wetland ecology .
(23) You have made yourselves pure by obeying the truth .
(24) Demas loved this world too much .
Argument type: Modal
Description: This type applies to modal auxiliary verbs, such as ‘can’, ‘will’, and ‘might’, which indicate some aspect of the event (25). This category is defined mostly syntactically, as the semantic contribution depends on which modal verb is chosen.
(25) Outdoors , they can also personally experience wetland ecology .
Argument type: Cause
Description: This type applies to phrases which indicate the cause of an event or the reason it happened (26).
(26) But they gave much because of their great joy .
Argument type: Temporal
Description: This type applies to phrases which indicate when an event happens (27).
(27) People send me emails all of the time .
Argument type: EventModifier/Purpose
This type applies to various phrases which indicate a modification or comment about an event, such as the degree of certainty of assertion (28), (29), secondary predication of some other entity named in the sentence (30), or the purpose of an event (31),
(28) Well Republicans certainly think so .
(29) You probably knew that .
(30) So you still have your office as your office ?
(31) I called Atlanta to get background on this guy .
Argument type: Negative
This type applies to phrases of negation, such as ‘not’ (32) or ‘never’ (33), which deny some aspect of what the rest of the sentence asserts.
(32) These are not certain , either .
(33) There the fire never stops .
We believe that this set of argument/predicate relation categories effectively captures the distinctions that our semantic role labeler makes. We hope this guide is a useful reference to using the tool.
References
Bonial, C., Babko-Malaya, O., Choi, J. D., Hwang, J., and Palmer, M. (2010). Propbank annotation guidelines. Center for Computational Language and Education Research Institute of Cognitive Science University of Colorado at Boulder.
