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University of Alberta 04/18/23 1
Governing Category and Coreference
Dekang Lin
Department of Computing Science
University of Alberta
University of Alberta 04/18/23 2
Constraints on Coreference Relationships
John hurt himself *Miss Marple hurt himself John likes him John said Peter likes him She likes Susan She said Jan likes Susan
University of Alberta 04/18/23 3
C-command
C-command is a relationship between two nodes in a parse tree
c-commands if
1. does not dominate 2. the parent of dominates
dominates if is an ancestor of in the parse tree
NP
Det N’
N PP
P NP
AP N
A
a
forecast
of
future
returns
University of Alberta 04/18/23 5
Binding
A noun phrase is bound to another noun phrase if and are co-indexed (refer to the same entity) c-commands .
Examples John hurt himself John likes him John said Peter likes him She likes Susan She said Jan likes Susan
University of Alberta 04/18/23 6
Classification of NPs
NPs can be classified into the following categories according to their binding property: R-Expressions: Mary, the policeman, the company Pronominals: he, she, you, her, his, ... Reciprocals and reflexives: each other, himself, herself, ...
Chomsky82:
-anaphor +anaphor
-pronominal R-expressions Refl/Recp
+pronominal Pronominals PRO
University of Alberta 04/18/23 7
Binding Theory
Tentative Definition: The local domain of phrase is the smallest clause that contains the phrase.
Principle A: A NP with [+anaphor] must be bound within its local domain.
Principle B: A NP with [+pronominal] must not be bound within its local domain.
Principle C: A NP with [-anaphor -pronominal] must not be bound.
University of Alberta 04/18/23 8
Examples
John hurt himself John likes him John said Peter likes him She likes Susan She said Jan likes Susan *John thinks that himself is the best candidate John considered himself to be the best candidate John said that pictures of himself were on sale. Peter read John’s story about himself/him. *John wanted Mary to take a picture of himself.
University of Alberta 04/18/23 9
Government
Government is a relationship between two nodes in a parse tree.
governs if 1. is the head of a phrase and a potential governor 2. A phrase headed by dominates 3. There does not exist a such at governs and governs
Potential governors
All lexical categories: N, V, A, P Head of finite clauses
University of Alberta 04/18/23 10
Binding Theory (Revised)
The governing category of is the minimal phrase that contains , the governor of , and a subject (a NP at spec of an IP or a NP) that c-commands the governor.
Binding Theory Principle A: A NP with [+anaphor] must be bound within its
governing category. Principle B: A NP with [+pronominal] must not be bound
within its governing category. Principle C: A NP with [-anaphor -pronominal] must not be
bound.
University of Alberta 04/18/23 17
Binding and PRO
PRO is treated like lexical NPs John persuaded Maryi PROi to defend herself/*himself
Johni promised Mary PROi to defend himself/*herself
University of Alberta 04/18/23 18
Problem Cases
They knew/found that each other’s photos were on sale
Mary believes it is possible for herself to win Jill knew that nothing could obliterate the memory
of those photographs of herself [Napoli93] Ralph considers Mary inferior to himself
[Napoli93, p.519] ?Ralph considers John inferior to himself
University of Alberta 04/18/23 19
Local Domain (Revisted Again)
The Local Domain of is the minimal phrase that contains , its governor, and a subject (a NP at spec of an IP or a NP) that c-commands the governor and is accessible to .
University of Alberta 04/18/23 20
Non-referential NPs
Some NPs, such as nothing, there, it (expletive), are not accessible to anything.
University of Alberta 04/18/23 22
A Singular Nouns is not Accessible to “Each Other”
Pollard&Sag 94, p.245 John and Mary know that the journal had rejected each
other’s papers Why are John and Mary letting the honey drip on each
other’s feet [Chomsky 1973: 261] John suggested that tiny gilt-framed portraits of each
other would make ideal gifts for the twins The agreement that Iran and Iraq reached guaranteed
each other’s trading rights in the disputed waters until the year 2010
University of Alberta 04/18/23 23
Inaccessibility between Argumentsof a Predicate
If two arguments of a predicate are known to be distinct a priori, they are not accessible to each other. Ralph considers Mary inferior to himself [Napoli93,
p.519] *Ralph considers Mary fond of himself [Napoli93,
p.519]
University of Alberta 04/18/23 24
Accessibility
A is inaccessible to B if, disregarding agreement features, A could not possibly bind B.
Otherwise, A is accessible to B
University of Alberta 04/18/23 25
Exceptions to Principle B
Example Jill took her brother with her to the market
[Napoli93,513]
The use of “her” instead of “herself” may be explained by Full Interpretation “X took Y with Z” implies Z=X. the only purpose to use an anaphor as Z is to indicate
Z=X
University of Alberta 04/18/23 26
Exceptions to Principle C
ABC applauded the new contract, which gave the network more flexibility.
The company said it plans to use the sale proceeds to invest in business opportunities more closely identified with the company’s “refocused direction.”
University of Alberta 04/18/23 27
Anaphors without Governing Category
Not all anaphors have governing categories: A letter from Mary about herself was in the mail
[Kuno93, p.138] Those nude pictures of himself ruined John’s career.
[Napoli93, p550]
Revised Principle A: If an anaphor has a governing category, it must be
bound within its governing category. If an anaphor has no governing category, it must be co-
indexed with the most accessible NP in the context.
University of Alberta 04/18/23 28
The picture of himselfi in Newsweek bothered Johni
*The picture of himselfi in Newsweek bothered John’si father
The picture of himselfi in Newsweek dominated John’si thoughts
The picture of himselfi in Newsweek shattered the piece of mind that Johni had spent the last six months trying to restore.
Examples of Anaphor without GC
University of Alberta 04/18/23 29
Conclusion
We proposed a definition of Governing Category that is simpler and has better empirical coverage than Chomsky’s earlier definition.
University of Alberta 04/18/23 30
Unresolved Problems
John made sure it was clear to Mary that the picture of himself was already sold
Mary made sure it was clear to John that the picture of himself was already sold
Bill suspected the silence meant that a picture of himself would soon be on the post office wall [Pollard&Sag94, p.268]
University of Alberta 04/18/23 31
Problems with C-command
Pollard&Sag94 pointed out the following problems Mary talked to John about himself *Mary talked to himi about Johni
Possible solution redefine c-command so that prepositions do not block c-
command introduce linear order requirement in c-command
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