University of Alberta6/3/20151 Governing Category and Coreference Dekang Lin Department of Computing Science University of Alberta

6/3/20152 Constraints on Coreference Relationships l John hurt himself l *Miss Marple hurt himself l John likes him l John said Peter likes him l She likes Susan l She said Jan likes Susan

University of Alberta6/3/20153 C-command l 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 DetN’ NPP PNP AP N A a forecast of future returns

University of Alberta6/3/20154

University of Alberta6/3/20155 Binding A noun phrase  is bound to another noun phrase  if  and  are co-indexed (refer to the same entity)  c-commands . l Examples © John hurt himself © John likes him © John said Peter likes him © She likes Susan © She said Jan likes Susan

University of Alberta6/3/20156 Classification of NPs l 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,... l Chomsky82: -anaphor+anaphor -pronominalR-expressionsRefl/Recp +pronominalPronominalsPRO

University of Alberta6/3/20157 Binding Theory l Tentative Definition: The local domain of phrase is the smallest clause that contains the phrase. l Principle A: A NP with [+anaphor] must be bound within its local domain. l Principle B: A NP with [+pronominal] must not be bound within its local domain. l Principle C: A NP with [-anaphor -pronominal] must not be bound.

University of Alberta6/3/20158 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 Alberta6/3/20159 Government l 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  l Potential governors © All lexical categories: N, V, A, P © Head of finite clauses

University of Alberta6/3/ 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. l 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 Alberta6/3/ Example 1 l John likes himself

University of Alberta6/3/ Example 2 l Mary likes John’s picture of himself

University of Alberta6/3/ Example 3 l *John wanted Mary to take a picture of himself

University of Alberta6/3/ Example 4 l John considers himself to be the best

University of Alberta6/3/ Example 5 l John said that pictures of himself were on sale

University of Alberta6/3/ Example 6 l *Mary believes herself can afford the car

University of Alberta6/3/ Binding and PRO l PRO is treated like lexical NPs © John persuaded Mary i PRO i to defend herself/*himself © John i promised Mary PRO i to defend himself/*herself

University of Alberta6/3/ Problem Cases l They knew/found that each other’s photos were on sale l Mary believes it is possible for herself to win l Jill knew that nothing could obliterate the memory of those photographs of herself [Napoli93] l Ralph considers Mary inferior to himself [Napoli93, p.519] l ?Ralph considers John inferior to himself

University of Alberta6/3/ 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 Alberta6/3/ Non-referential NPs l Some NPs, such as nothing, there, it (expletive), are not accessible to anything.

University of Alberta6/3/ Each Other’s l “Each other’s” is not accessible to “each other’s”

University of Alberta6/3/ A Singular Nouns is not Accessible to “Each Other” l 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 Alberta6/3/ Inaccessibility between Arguments of a Predicate l 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 Alberta6/3/ Accessibility l A is inaccessible to B if, disregarding agreement features, A could not possibly bind B. l Otherwise, A is accessible to B

University of Alberta6/3/ Exceptions to Principle B l Example © Jill took her brother with her to the market [Napoli93,513] l 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 Alberta6/3/ Exceptions to Principle C l ABC applauded the new contract, which gave the network more flexibility. l 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 Alberta6/3/ Anaphors without Governing Category l 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] l 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 Alberta6/3/ l The picture of himself i in Newsweek bothered John i l *The picture of himself i in Newsweek bothered John’s i father l The picture of himself i in Newsweek dominated John’s i thoughts l The picture of himself i in Newsweek shattered the piece of mind that John i had spent the last six months trying to restore. Examples of Anaphor without GC

University of Alberta6/3/ Conclusion l We proposed a definition of Governing Category that is simpler and has better empirical coverage than Chomsky’s earlier definition.

University of Alberta6/3/ Unresolved Problems l John made sure it was clear to Mary that the picture of himself was already sold l Mary made sure it was clear to John that the picture of himself was already sold l Bill suspected the silence meant that a picture of himself would soon be on the post office wall [Pollard&Sag94, p.268]

University of Alberta6/3/ Problems with C-command l Pollard&Sag94 pointed out the following problems © Mary talked to John about himself © *Mary talked to him i about John i l Possible solution © redefine c-command so that prepositions do not block c- command © introduce linear order requirement in c-command