1. Event Semantics Martha Palmer Orin Hargraves University of Colorado LING 7800/CSCI 7000-017 February 19, 2013

2. What's an Event? ● Not a person, not a physical object, not a state (but an entity? Hmmm...)

3. What's an Event? ● Not a person, not a physical object, not a state (but an entity? Hmmm...) ● If there’s a change of state (COS), there’s probably an event, but not having a clear COS does not mean there’s no event.

4. What's an Event? ● Not a person, not a physical object, not a state ● (but an entity? Hmmm...) ● If there’s a change of state (COS), there’s probably an event, but not having clear a COS does not mean there’s no event. ● Is agency or causality required for there to be an event? Debatable.

5. What's an Event? ● Not a person, not a physical object, not a state (but an entity? Hmmm...) ● If there’s a change of state (COS), there’s probably an event, but not having a COS does not mean there’s no event. ● Is agency or causality required for there to be an event? Debatable. ● Davidson (1967) formalized and Parsons (1990) developed the idea that action verbs imply a quantifiable event.

6. Event v. Object ● “happen” ● “exist”

7. Event v. Object ● “happen” ● clear time boundaries ● “exist” ● clear space boundaries

8. Event v. Object ● “happen” ● clear time boundaries ● indistinct or irrelevant space boundaries ● “exist” ● clear space boundaries ● no time boundaries?

9. Event v. Object ● “happen” ● clear time boundaries ● indistinct or irrelevant space boundaries ● take up time ● “exist” ● clear space boundaries ● no time boundaries? ● take up space

10. Event v. Object ● “happen” ● clear time boundaries ● indistinct or irrelevant space boundaries ● take up time ● can't move (fixed in time) ● “exist” ● clear space boundaries ● no time boundaries? ● take up space ● can move (space has voids)

11. Event v. Object ● “happen” ● clear time boundaries ● indistinct or irrelevant space boundaries ● take up time ● can't move (fixed in time) ● represented by verbs and deverbal nouns ● “exist” ● clear space boundaries ● no time boundaries? ● take up space ● can move (space has voids) ● represented by nouns

12. Event as Object Metaphor Despite lacking many objectlike qualities, human perception and language are geared to perceive events as quantifiable abstractions, or entities (objectlike things). Even children get it. “I asked you to clean up your room and you didn't do it.” Linguistic analysis supports the identification of events algorithmically, using semantic and grammatical rules pertinent to other kinds of analysis.

13. Event and Object, Redux ● Objects are prime actors in events ● Objectless events are uncommon (conceptually difficult, grammatically impossible) ● Eventless objects are also difficult to conceive (how did the objects get here?) ● Events make up the life of objects, or put another way... ● Objects depend on events (or events require participants who are doing something; Parsons, 1990)

14. What Happened? ● Mary had a little lamb whose fleece was white as snow; and everywhere that Mary went, the lamb was sure to go. (Mother Goose)

15. What Happened? ● Mary had a little lamb whose fleece was white as snow; and everywhere that Mary went, the lamb was sure to go. (Mother Goose) ● Hail Mary, full of grace, the Lord is with thee; blessed art thou amongst women, and blessed is the fruit of thy womb, Jesus. (Catholicism)

16. What Happened? ● Mary had a little lamb whose fleece was white as snow; and everywhere that Mary went, the lamb was sure to go. (Mother Goose) ● Hail Mary, full of grace, the Lord is with thee; blessed art thou amongst women, and blessed is the fruit of thy womb, Jesus. (Catholicism) ● And then along comes Mary. And does she want to see the stains, the dead remains of all the pains she left the night before? (The Association, 1966)

17. Event Detection Challenges ● Time modifiers are highly idiosyncratic across languages (consider: already, yet, since, just)

18. Event Detection Challenges ● Time modifiers are highly idiosyncratic across languages (consider: already, yet, since, just) ● Verb tense, mood, and aspect markers are often ambiguous

19. Event Detection Challenges ● Time modifiers are highly idiosyncratic across languages (consider: already, yet, since, just) ● Verb tense, mood, and aspect markers are often ambiguous ● Regular polysemy presents practical challenges to event/entity/object identification

20. Event Detection Challenges ● Time modifiers are highly idiosyncratic across languages (consider: already, yet, since, just) ● Verb tense, mood, and aspect markers are often ambiguous ● Regular polysemy presents practical challenges to event/entity/object identification ● Different event annotation schemas require different levels of granularity

21. Event Detection Challenges ● Time modifiers are highly idiosyncratic across languages (consider: already, yet, since, just) ● Verb tense, mood, and aspect markers are often ambiguous ● Regular polysemy presents practical challenges to event/entity/object identification ● Different event annotation schemas require different levels of granularity ● DocTime may not be precisely determinable

22. Some real-life event questions ● How domain- or genre-specific can event annotation schemas be?

23. Some real-life event questions ● How domain- or genre-specific can event annotation schemas be? ● Events and relations: where is the line? (wedding > marriage > spousal relation)

24. Some real-life event questions ● How domain- or genre-specific can event annotation schemas be? ● Events and relations: where is the line? (wedding > marriage > spousal relation) ● Can “atomic” events be annotated like aggregate events?

25. Some real-life event questions ● How domain- or genre-specific can event annotation schemas be? ● Events and relations: where is the line? (wedding > marriage > spousal relation) ● Can “atomic” events be annotated like aggregate events? ● What features in PropBank aid/hinder event identification? (ditto: WN, VN, FN)

26. Some real-life event questions ● How domain- or genre-specific can event annotation schemas be? ● Events and relations: where is the line? (wedding > marriage > spousal relation) ● Can “atomic” events be annotated like aggregate events? ● What features in PropBank aid/hinder event identification? (ditto: WN, VN, FN) ● How can verb features (tense, aspect, modality, etc.) be leveraged to enhance event detection?

27. Parsons' Event Semantics ● A proper noun…refers to its bearer, which is…a “thing” ● Common nouns…do not stand for things…they stand for kinds of things. ● Much the same is true of verbs; ordinary verbs stand for kinds of actions or states ● “It is a matter of some complexity to formulate a theory of how we use them to talk about particular actions and states.”

28. Parsons' Event Semantics ● The arguments of an action verb give existential quantification to the eventuality that the verb represents. ● An action verb in situ (and absent elements that generalize it) contains an implicit logical argument, which is the event itself. ● Parsons (disagreeing with Davidson) would represent the event itself as an argument, not a relation, thus:

29. Parsons' Event Semantics Davidson: ● have(Mary, lamb, e h ) Parsons: ● have(e h ), Agent(e h, Mary) Theme(e h, lamb)

30. Parsons' Event Semantics Davidson: instrumental, local, and temporal adverbials can be analyzed as first order predicates that add information about events. Parsons: Event variables can be used in the formalization of all predicate adverbials, including manner adverbs. Which model lends itself to better implementation in NLP, taking advantage of existing lexical resources?