Embedded Clauses in TAG Embedded Clauses Matrix Clause
Embedded Clauses in TAG
Embedded Clauses Matrix Clause S NP VP V S-bar Embedded Clause S COMP We think that NP VP they have left.
How we know that the semantic role assignments are different with Seem and Try • The cat seems to be out of the bag. • There seems to be a problem. • That seems to be my husband. • The doctor seemed to examine Sam. • Sam seemed to be examined by the doctor. • The cat tried to be out of the bag. • *There tried to be a problem. • That tried to be my husband. • The doctor tried to examine Sam. • Sam tried to be examined by the doctor.
Raising to subject S NP S VP V NP S-bar VP V VP-bar S COMP It seems that NP VP VP COMP they have left. They seem to have left.
S NP VP V VP-bar Two ways to represent that “seem” and “leave” share a subject. VP COMP They seem to have left. S NP VP V S NP They seem e VP to have left. Subj Verb Complement they seem subj verb leave
Comparison • Second method: – Allow empty strings as terminal nodes in the tree. – An empty string needs to take the place of the missing subject of the lower clause. – The empty string is linked to the subject of the main clause to show that the main and embedded clauses share a subject. – The tree represents: word order, constituent structure, grammatical relations, semantic roles. • First method: – No empty strings in the tree. – The tree represents only word order and constituent structure. – Grammatical relations and semantic roles are represented in a separate structure. – Structure sharing in the representation of grammatical relations shows that the two verbs share a subject. • Is one method simpler than the other? – No. Both methods have to represent word order, semantic relations, grammatical relations, and semantic roles. • People who argue that one is simpler are usually wrong – they don’t know how to count steps in a derivation.
Two ways to represent that “try” and “leave” share a subject. S NP VP V VP-bar Subj Verb Complement VP COMP They try to they seem subj verb leave. S NP PRO is an empty string, but not the same kind of empty string as e VP V S NP They(i) try VP Coindexing indicates that PRO refers to “they”. PRO(i) to leave.
“Seem” type verbs in TAG VP S NP VP V John Adjunction site AP to be happy Initial Tree V VP seem Auxiliary Tree These trees represent the number of arguments for each verb: “Seem” has one argument, represented as a VP. “To be happy” has one argument, “John”.
VP S NP VP Adjunction site V seem VP V John AP to be happy VP
S NP V VP VP V VP seems V Adjunction VP seem AP to be happy VP V John VP AP to be happy John This tree shows word order and constituent structure. It also shows that “John” is the subject of “seem. ” It doesn’t show that “John” is the subject of “to be happy. ”
“Try” type verbs in TAG S S NP NP VP V John VP TO S PRO tried Auxiliary Tree Adjunction site VP leave Initial Tree These trees show the number of arguments for each verb: “Try” has two arguments. “Leave” has one argument.
S S NP VP V John Adjunction site tried S S NP VP TO PRO VP leave
S S NP VP V John Adjunction site S S tried. NP VP TO PRO VP leave
Adjunction is only allowed at the top S node so as not to mess up compositional semantics: After you put together “try to leave” you don’t want to have to take it apart again by inserting another verb like “expected” as in: John tried to expect to leave. Inserting “seem” into the middle of the tree doesn’t require you to disassemble any of the semantic pieces that were already assembled? S NP VP V John S tried. NP VP TO PRO VP leave
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