Week4-1Syntax

Syntax

• Language is more than a bag of words!
• Grammar rules apply to the categories and groups of words, not individual word
• Example - a sentence includes a subject and a predicate
• Learn the new word and its syntactic usage.

Defining the POS

• What do nouns typically have in common?
  
  • can be preceded by “the”
• Verbs can be preceded by can’t.
• Adjectives can be between “the” and a noun
• Determiners

Constituents

• Constituents are continuous
• Constituents are no-crossing, if 2 constituents share 1 word, then one of them must completely contain the other
• Each word is a constituent of itself

Constituent tests

• coordination test: if 2 parts can be connected by conjunctions, they are both constituents
• pronoun test: constituents can be replaced by corresponding pronouns
• question by repetition test
  
  • I have seen blue elephants
  • blue elephants? Yes
  • seen blue? No
  • seen blue elephants? Yes
• topicalization test
  
  • Blue elephants, I have seen.
• question test:
  
  • What have I seen?
• deletion test
• semantic test
• …

How to generate sentences?

• One way: tree structure
  
  1. Generate the tree structure first
  2. Fill the leaf nodes with terminals

PP ambiguity

The boy saw the woman with the telescope.

Repetition(*)

• JJ* = a sequence of zero or more JJ
• Are all sequences of adjectives allowed? No
  
  • a big red house YES
  • a red big house NO
• Adjective ordering in English depends on semantics!

Nested sentences

Birds fly. vs. I believe that birds fly.

Example
- I don’t recall whether I took the dog out.
- Do you know if the mall is still open?

Recursion

• S can generate VP, and VP can generate S.
• NP can generate PP, and PP can generate NP.
• Conjunctions of NPs and PPs

Meta-patterns(X-bar theory)

Auxiliaries

• Is “Aus V” a constituent? YES, pass the conjunction test.
  
  • I have seen elephants and will remember them forever.
• Recursion
  
  • VP -> Aux VP
    
    • Raj may have been sleeping.