Curs 3: Analiza unei lucrari

1
Curs 3 Analiza unei lucrari

• O prima sedinta de avocati ai diavolului

2
The Right Frontier Constraint Holds
Unconditionally

• Dan Cristea
• Lucrare care ar fi trebuit sa fie prezentata la
  MAD-05, Berlin
• www.infoiasi.ro/dcristea/publications.html

3
The Right Frontier Constraint

• As an attachment constraint in an incremental
  development of a tree structure
• adjunction of an auxiliary tree on a node of a
  developing tree can be made only on a node
  belonging to the right frontier of the developing
  tree

4
The Right Frontier Constraint

• As a referential constraint defining the regions
  of the discourse model

5
Anaphora and Discourse Constraints Nicholas
Asher (University of Texas) 

• Over a decade of work on the relation between
  semantics and discourse has established the Right
  Frontier Constraint as a well confirmed
  linguistic constraint on discourse structure.
  After formulating the Right Frontier Constraint
  in a precise fashion and reviewing the evidence
  for if from a variety of sources, I want to
  consider some challenges to it. I will look at
  two sorts of troubling phenomena the first is
  the way presuppositions and anaphoric definite
  descriptions can affect discourse structure and
  hence the Right Frontier Constraint, the second
  has to do with the way locality can sometimes
  seem to override the Right Frontier Constraint. I
  will then reformulate the Right Frontier
  Constraint so as to take account of the data.

6
RFC can be violated!

• From (SassenKühnlein, 2005)
• a. B would you say that Im indeed only jealous?
  
• c. B do you have another consultation hour
  scheduled soon?
• b. A Try to be with yourself after all youre
  heading for your final degree!
• b. B mhm, well, but concentrating on my studies
  often doesnt work
• c. A yes, always on Monday.
• a. A only jealous that would already suffice as
  problem, but I think there is more to it.

7
RFC as conditional

• v. CICling 2005

8
Principle of Sequentiality

• A left-to-right reading of the terminal frontier
  of a discourse tree associated to a text
  corresponds to the span of text analysed, in the
  same linear order.

(Marcu, 2000), etc.
9
Operations inspired by TAG
10
The Right Frontier Property

• At any step of an incremental discourse parsing,
  if the DT does not contain substitution nodes,
  the SP is observed if and only if all operations
  are adjoinings of left-footed ATs onto nodes of
  the right frontier of the DT.

11
The Right Frontier Property
auxiliary tree
transformed tree
developing tree
Y
Y
X
?y
?
?0
?0
X
?1
?y
?1
Adjunction of a left-footed AT on the RF of the DT
12
The Right Frontier Property
auxiliary tree
transformed tree
developing tree
Y
Y
X
?a2
?a1
?
?0
?0
X
?1
?a1
?a2
?1
Adjunction of an AT which is not left-footed
13
The Right Frontier Property
auxiliary tree
transformed tree
developing tree
Y
Y
Y
X
?a2
?a1
?
?2
?0
?2
?0
X
?1
?a1
?a2
?1
Adjunction of an AT on a node which does not
belong to the RF of the DT
14
RFC can be violated!

• a. B Ive recently felt confused when seeing
  Maria talking with Michael.
• b. B The reason Im asking your advise is that
  Ill have my degree in June and right now Im not
  in my best shape.
• a. A oh yea, then, what we have here is a nice
  case of jealousy.
• a. B would you say that Im indeed only jealous?
  
• c. B do you have another consultation hour
  scheduled soon?
• b. A Try to be with yourself after all youre
  heading for your final degree!
• b. B mhm, well, but concentrating on my studies
  often doesnt work
• c. A yes, always on Monday.
• a. A only jealous that would already suffice as
  problem, but I think there is more to it.

15
RFC can be violated!

• a. B Ive recently felt confused when seeing
  Maria talking with Michael.
• b. B The reason Im asking your advise is that
  Ill have my degree in June and right now Im not
  in my best shape.
• a. A oh yea, then, what we have here is a nice
  case of jealousy.
• a. B would you say that Im indeed only jealous?
  
• c. B do you have another consultation hour
  scheduled soon?
• b. A Try to be with yourself after all youre
  heading for your final degree!
• b. B mhm, well, but concentrating on my studies
  often doesnt work
• c. A yes, always on Monday.
• a. A only jealous that would already suffice as
  problem, but I think there is more to it.

16
RFC can be violated!

• a. B Ive recently felt confused when seeing
  Maria talking with Michael.
• b. B The reason Im asking your advise is that
  Ill have my degree in June and right now Im not
  in my best shape.
• a. A oh yea, then, what we have here is a nice
  case of jealousy.
• a. B would you say that Im indeed only jealous?
  
• c. B do you have another consultation hour
  scheduled soon?
• b. A Try to be with yourself after all youre
  heading for your final degree!
• b. B mhm, well, but concentrating on my studies
  often doesnt work
• c. A yes, always on Monday.
• a. A only jealous that would already suffice as
  problem, but I think there is more to it.

17
RFC can be violated!

• a. B Ive recently felt confused when seeing
  Maria talking with Michael.
• b. B The reason Im asking your advise is that
  Ill have my degree in June and right now Im not
  in my best shape.
• a. A oh yea, then, what we have here is a nice
  case of jealousy.
• a. B would you say that Im indeed only jealous?
  
• c. B do you have another consultation hour
  scheduled soon?
• b. A Try to be with yourself after all youre
  heading for your final degree!
• b. B mhm, well, but concentrating on my studies
  often doesnt work
• c. A yes, always on Monday.
• a. A only jealous that would already suffice as
  problem, but I think there is more to it.

18
RFC can be violated!

• a. B Ive recently felt confused when seeing
  Maria talking with Michael.
• b. B The reason Im asking your advise is that
  Ill have my degree in June and right now Im not
  in my best shape.
• a. A oh yea, then, what we have here is a nice
  case of jealousy.
• a. B would you say that Im indeed only jealous?
  
• c. B do you have another consultation hour
  scheduled soon?
• b. A Try to be with yourself after all youre
  heading for your final degree!
• b. B mhm, well, but concentrating on my studies
  often doesnt work
• c. A yes, always on Monday.
• a. A only jealous that would already suffice as
  problem, but I think there is more to it.
• A to this you have to find a solution
  immediately.

19
RFC can be violated!

• a. B Ive recently felt confused when seeing
  Maria talking with Michael.
• b. B The reason Im asking your advise is that
  Ill have my degree in June and right now Im not
  in my best shape.
• a. A oh yea, then, what we have here is a nice
  case of jealousy.
• a. B would you say that Im indeed only jealous?
  
• c. B do you have another consultation hour
  scheduled soon?
• b. A Try to be with yourself after all youre
  heading for your final degree!
• b. B mhm, well, but concentrating on my studies
  often doesnt work
• c. A yes, always on Monday.
• a. A only jealous that would already suffice as
  problem, but I think there is more to it.
• A to this you have to find a solution
  immediately.

20
RFC can be violated!

• a. B Ive recently felt confused when seeing
  Maria talking with Michael.
• b. B The reason Im asking your advise is that
  Ill have my degree in June and right now Im not
  in my best shape.
• a. A oh yea, then, what we have here is a nice
  case of jealousy.
• a. B would you say that Im indeed only jealous?
  
• c. B do you have another consultation hour
  scheduled soon?
• b. A Try to be with yourself after all youre
  heading for your final degree!
• b. B mhm, well, but concentrating on my studies
  often doesnt work
• c. A yes, always on Monday.
• a. A only jealous that would already suffice as
  problem, but I think there is more to it.
• A to this you have to find a solution
  immediately.

21
r1
r2
r3
r4
r5
r6
22
Merge

• a1. A how was your trip to Brasov?
• b1. A oh, did I tell you? I have seen yesterday
  evening Michael in the disco.
• b2. A did you meet him anymore since you two
  split?
• a2. B. Fantastic! lots of nice guys and lot of
  fun.

23
Merge

• a1. A how was your trip to Brasov?
• b1. A oh, did I tell you? I have seen yesterday
  evening Michael in the disco.
• b2. A did you meet him anymore since you two
  split?
• a2. B. Fantastic! lots of nice guys and lot of
  fun.
• B wow, but, you know, he was too in that
  trip!

24
Merge of two DTs
r
r1
r1
r2
ab
r2
r
ab
25
Merge of two DTs
wow, but, you know, he was too in that trip!
26
Splitting

• ab1. A so, you didnt know that I finished with
  Michael?!
• ab2 A it happened last month after I came back
  from Mexico.
• a3. B oh, Im sorry, are you still mourning
  after him or you have already someone else?
• a4. A negative! Im ok but need a period of
  loneliness.
• a5. B you cannot resist long like this. I know
  you
• b3. B so, have you seen the pyramids there?

27
Splitting a DT
r2
r3
r1
A it happened last month after I came back from
Mexico.
B oh, Im sorry, are you still mourning after
him or you have already someone else?
r4
A so, you didnt know that I finished with
Michael?!
B you cannot resist long like this. I know you
A negative! Im ok and need a period of
loneliness.
r1
A so, you didnt know that I finished with
Michael?!
A it happened last month after I came back from
Mexico.
r1
r5
A so, you didnt know that I finished with
Michael?!
A it happened last month after I came back from
Mexico.
B so, have you seen the pyramids there?
28
Splitting a DT
r2
r3
r1
B oh, Im sorry, are you still mourning after
him or you have already someone else?
r4
A so, you didnt know that I finished with
Michael?!
B you cannot resist long like this. I know you
A negative! Im ok and need a period of
loneliness.
r5
A it happened last month after I came back from
Mexico.
B so, have you seen the pyramids there?
29
A problem
r2
r3
r1
A it happened last month after I came back from
Mexico.
B oh, Im sorry, are you still mourning after
him or you have already someone else?
r4
A so, you didnt know that I finished with
Michael?!
B you cannot resist long like this. I know you
A negative! Im ok and need a period of
loneliness.
B so, have you seen the pyramids there?
How could Mexico be evoked by there since it
belongs to a span which is closed ?
30
Referential means

• Weak
• pronouns (including zero)
• demonstratives
• Strong
• proper nouns
• noun phrases (bridges or coreferential)
• Nothing is really forgotten

31
Conclusions

• RFC holds!
• not only because a whole class of dedicated
  scholars have found examples to support it
• because there is a simple theoretical proof for
  it
• Discourse should be represented by graphs, not
  trees
• Not only chats, but long discourses too
• Graphs can represent multi-threads
• splitting a thread onto two
• merging two distinct threads onto one
• interruptions and flashbacks
• there are more developing Right Frontiers on a
  discourse graph
• hopping from a RF to another needs strong
  referential means