Embedded Clauses in TAG

1
Embedded Clauses in TAG
2
Embedded Clauses
Matrix Clause
Embedded Clause
3
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.

4
Raising to subject
5
S
Two ways to represent that seem and leave
share a subject.
NP VP
V VP-bar
Subj they Verb
seem Complement subj
verb leave
VP
COMP
They seem to have left.
S
NP VP
V S
NP VP
They seem e to have left.
6
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 dont know how to count steps in a
  derivation.

7
S
Two ways to represent that try and leave
share a subject.
NP VP
V VP-bar
Subj they Verb
seem Complement subj
verb leave
VP
COMP
They try to leave.
S
PRO is an empty string, but not the same kind of
empty string as e ? Coindexing indicates that
PRO refers to they.
NP VP
V S
NP VP
They(i) try PRO(i) to leave.
8
Seem type verbs in TAG
VP
V VP
seem
Auxiliary Tree
Initial 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.
9
S
NP VP
VP
V AP
to be happy
John
10
Adjunction
VP
This tree shows word order and constituent
structure. It also shows that John is the
subject of seem. It doesnt show that John
is the subject of to be happy.
11
Try type verbs in TAG
Initial Tree
Auxiliary Tree
These trees show the number of arguments for each
verb Try has two arguments. Leave has one
argument.
12
S
13
S
14
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 dont 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 doesnt require you to disassemble any of
the semantic pieces that were already assembled?