Categories relations or individuals

1
Categories relations or individuals?

• What are the differences in representing collie
  as a relation vs. an individual?
• As a relation collie(lassie)
• Can reason only about members of the category
  collie, not about the category (FOPC only allows
  terms, not predicates, as arguments of
  predicates cannot make true/false statements
  about predicates) goodWithKids(lassie).
• As an individual ISA(lassie,collie)
• Can make statements about both categories and
  individual members of categories
• goodWithKids(lassie)
• goodWithKids(collie)

2
Reification

• Reification is the technique we used to make
  collie an individual reification is sometimes
  called objectification.
• ISA is a member-class relationship
• ISA(lassie, collie)
• AKO (A Kind Of) is a subclass-superclass
  relationship
• AKO(collie, dog)
• AKO(dog, mammal)
• AKO(mammal, animal)

3
Events relations or individuals?

• We face the same question for events as we did
  for categories.
• Should we represent events as relations or as
  individuals?
• Looking at syntax it seems that representing the
  event as a relation is natural (think of
  subcategorization frames).
• But, this implies we cant reason about events!
• Take the same approach as with categories reify!

4
Basic problem (p. 524-525)

• Examples with the verb to eat
• I ate.
• I ate a turkey sandwich.
• I ate a turkey sandwich at my desk.
• I ate at my desk.
• I ate lunch.
• I ate a turkey sandwich for lunch.
• I ate a turkey sandwich for lunch at my desk.
• All describe an event of eating.
• What is a reasonable representation?

5
Events as relations

• Suppose we decide that events should be
  represented as relations.
• Q What is the arity ( arguments) of the
  predicate?
• A It is different in different examples!
• Eating1(Speaker)
• Eating2(Speaker, TurkeySandwich)
• Eating3(Speaker, TurkeySandwich, Desk)
• Eating4(Speaker, Desk)
• Eating5(Speaker, Lunch)
• Eating6(Speaker, TurkeySandwich, Lunch)
• Eating7(Speaker, TurkeySandwich, Lunch, Desk)

6
Reasoning problem

• While we can build such representations, they do
  not possess the desired characteristics.
• For example, we cannot reason with these
  representations to learn that they all describe
  the same type of event (an eating event)
• Eating1 ? Eating2 ? Eating3 ? Eating4 ? Eating5 ?
  Eating6 ? Eating7
• Can solve this problem by introducing meaning
  postulates, such as,
• ?w,x,y,z Eating7(w,x,y,z) ? Eating6(w,x,y)
• Such a solution does not scale well (since these
  have to be explicitly encoded into knowledge
  base).

7
Additional problems

• Assumes that underlying event always has four
  arguments (eater, food, meal, location)
• but surely you can eat outside of regular meal
  times
• Cant express that two (partial) descriptions are
  about the same event
• ?w,x Eating(Speaker, w, x, Desk)
• ?w,x Eating(Speaker, w, Lunch, x)
• ?w Eating(Speaker, w, Lunch, Desk)

8
Reification of event is a better solution

• Compare the following two representations of I
  ate a Turkey sandwich
• ?w,x Eating(Speaker, TurkeySandwich, w, x)
• ?e ISA(e,Eating)?Eater(e,Speaker)?Eaten(e,TurkeySa
  ndwich)
• Advantages
• There is no need to specify a fixed number of
  arguments for a given surface predicate, rather
  as many roles and fillers can be glued on as
  appear in the input. p. 527
• No more roles are postulated than are mentioned
  in the input. p. 527
• The logical connections among closely related
  examples is satisfied without the need for
  meaning postulates. p. 527

9
Time and events

• Consider the following three examples (cf
  examples on page 528)
• I will arrive in Buffalo.
• I am arriving in Buffalo.
• I arrived in Buffalo.
• They all describe an event of arriving
• ?e ISA( e, Arriving ) ? Arriver( e, Speaker ) ?
  Destination( e, Buffalo )
• What makes them different is the time of the
  event.

10
Representing the time of an event

• ?e,i,t ISA(e,Arriving) ? Arriver(e,Speaker) ?
  Destination(e,Buffalo) ? IntervalOf(e,i) ?
  EndPointOf(i,t) ? Precedes(Now,t)
• ?e,i,t ISA(e,Arriving) ? Arriver(e,Speaker) ?
  Destination(e,Buffalo) ? IntervalOf(e,i) ?
  MemberOf(i,Now)
• ?e,i,t ISA(e,Arriving) ? Arriver(e,Speaker) ?
  Destination(e,Buffalo) ? IntervalOf(e,i) ?
  EndPointOf(i,t) ? Precedes(t,Now)

11
Representing time

• Reichenbach (1947)
• E is the event time
• R is the reference time
• U is the utterance time
• See diagram on page 530.

12
Examples

• Simple past (RE lt U)
• Present (REU)
• Simple future (RU lt E)
• Past perfect (EltRltU)
• Present perfect (EltRU)
• Future perfect (UltEltR)

• I ate.
• I eat.
• I will eat.
• I had eaten.
• I have eaten.
• I will have eaten.

13
Aspect

• The aspect of an event describes
• whether event is ongoing or completed
• whether it occurs at a point in time or over an
  interval of time
• whether its completion results in a change in the
  state of the world
• Events are classified as one of
• state
• activity
• accomplishment
• achievement

14
States I

• States are like snapshots of the world at a
  given instant. They lack a natural culmination
  or end point, and their subject is perceived not
  as an agent (as doing something) but as an
  experiencer (as experiencing something).
• Meaning and Grammar An Introduction to
  Semantics by Chierchia and McConnell-Ginet,
  p. 353

15
States II

• Examples
• John is drunk.
• John knows Latin.
• Diagnostics
• not good in progressive
• John is being drunk.
• John is knowing Latin.
• not good in imperative
• Be drunk!
• Know Latin!

16
Activities I

• Activities share with states the property of
  lacking a natural culmunation. Yet they are
  agentive in that they typically involve a subject
  doing something. They cannot in general be
  viewed as instantaneous snapshots of the world.
• ibid, p. 353

17
Activities - II

• Examples
• John is kicking.
• John is studying.
• Diagnostics
• fine in progressive (see above!)
• fine in imperatives
• Kicker harder!
• Study longer!

18
Accomplishments I

• accomplishment expressions describe events that
  have a natural end point and result in a
  particular state. p. 532
• Examples p. 532
• He booked me a reservation.
• United flew me to New York.

19
Accomplishments II

• Diagnostic stop p. 532
• I stopped living in Brooklyn. activity
• She stopped booking my flight. accomplishment
• Inferences?
• I lived in Brooklyn.
• but not She booked my flight. (intended state
  was not reached)
• Diagnostic temporal adverbials p.533
• I lived in Brooklyn in a year. activity
• She booked a flight in a minute. accomplishment

20
Achievements I

• Achievement expressions are similar to
  accomplishments in that they result in a state.
  Unlike accomplishments, achievement events
  are though of as happening in an instant, and are
  not equated with any particular activity leading
  up to the state. p. 533

21
Achievements II

• Examples
• She found her gate.
• I reached New York.
• Diagnostic temporal adverbial p. 533
• I lived in New York for a year.
  activity/accomplishment
• I reached New York for a few minutes.
  achievement
• Diagnostic stop p. 533
• I stopped booking my flight. accomplishment
• I stopped reaching New York. achievement