Syntactic Parsing - Dependency Structures Flashcards
What 2 ways can syntactic ambiguity be brought about?
- Multiple interpretations due to multiple meanings
- preposition attached to more than one token
“I saw the man on the hill [with] a telescope”
What is a dependency?
an asymmetric binary linking two tokens.
One is the head and the other is the dependent
What is the head and what is the dependent?
Head- is the main verb in a verb phrase or the main noun in a noun phrase
What are the other words for the head-dependent relationship?
superior-inferior
governor-modified
regent-subordinate
How do we know if something is a head or a dependent?
The dependents modify the head
What is a dependency graph?
nodes are the tokens and edges are the relation type labels
What are the different notation structures for dependency relationships?
horizontal (arrows one way or the other)
tree of tokens
tree of POS tagged tokens
machine readable (inline annotation)
nmod/amod
phrase that modifies a noun phrase
where is the nmod relationship in “sam eats red meat”
nmod(red, meat)
aux
non-main verb of a clause
where is the aux relationship in “he should leave”
aux(leave, should)
cc
coordination- connects element of a conjunct and coordinating word
where is the cc relationship in “they should either ski or snowboard”
cc(ski,or)
det
between the head of a np and its determiner
where is the det relationship in “the man is here”
det(man, the)
obj/dobj
between a verb and a np denoting the entity acted upon
where is the obj relationship in “she gave me a raise”
obj(gave,raise)
iobj
between a verb and a np acting as an indirect object
where is the iobj relationship in “she gave me a raise”
iobj(gave, me)
vmod
phrase that modifies a verb phrase
where is the vmod relationship in “genetically modified food”
vmod(modified, genetically)
sbj/nsubj
between a verb and a np denoting the entity that serves as subject or agent
where is the sbj relationship in “clinton defeated cole”
sbj(defeated, clinton)
pobj/pc
object of preposition
head of np following a proposition
where is the pobj relationship in “I sat on the chair”
pobj(on, chair)
p/punct
punctuation. between the head of the sentence (the root) and punctuation
where is the punct relationship in “go home!”
punct(go, !)
A dependency structure is endocentric if…
it fulfils the same linguistic function as one of its parts.
These are not required
A dependency structure is exocentric if…
it does not fulfil the same linguistic function as one of its parts.
These are required
Endocentric dependency structures? (2)
vmod amod
Exocentric dependency structures? (2)
subj, obj
What is verb valency?
Certain verbs require certain types of dependents
what is univalent, give an example
1 subject e.g. “dance”, danced(she)
what is divalent, give an example
1 subject, 1 object e.g. “ate”, ate(he,chocolates)
what is trivalent, give an example
1 subject, 2 objects e.g. “gave”, gave(he, document, her)
what is avalent, give an example
no subjects e.g. “rains”, it rains, rains()
What is a predicate argument structure (PAS)?
A generalisation of verb valency
How is predicate argument structure (PAS) different to verb valency?
predicates can be any POS, with arguments specified using an argument number.
