Structural Analysis of Text

• Global:

  Flying planes made her duck

  1. the airplanes made her change her position
  2. the act of piloting made her change her position
  3. piloting turned her into a duck
  4. the airplanes caused her duck (the animal) to exist
  5. the act of piloting made her duck exist
• Local:

  The company that bought [Scicon sold VIM].

  Is [Scicon sold VIM] a proposition? Implications on IR.

• Definition of constituent. When is a group a constituent?

     [John] [   [eats] [an apple]]
     [NP  ] [VP [V   ] [NP      ]]  (embedded)
     [NP  ]     [V   ] [NP      ]   (flat)
  

• The definition of constituency depends on the goal of the analysis. Syntactic constituents, Informational constituents (given/new or theme/rheme constituents, intonation constituents. Questions raised:
  1. Is there a connection between different structural dimensions? ie, Must a theme/rheme constituent also be a proper syntactic constituent?
  2. How do you define empirical tests for the determination of constituents?
• Are there discontinuous constituents?

     [Do] you [have] a hammer?
  

• Are there limits to the complexity of the structure of constituents?

• Structure determines meaning.
• Structure impacts on form (for example, agreement).

Structural vs Functional

• What is the structural position of a constituent?
• What is the function of a constituent within a sentence, the discourse?

• Obtain info or services
• Provide info or services
• Just be in touch
• Argument for a conclusion

• Syntax: structure, grammar.
• Semantics: meaning, propositional content.
• Pragmatics: usage, speech-acts, presuppositions
• Textual: contribute to extended coherent text.

Representation of meaning

1. Option1: meaning = procedure - set of instructions to achieve what the speaker wants. Simplest form:
   • meaning of command = procedure to carry out action
   • question = procedure to find answer
   • statement = proc to update the hearer's beliefs
   Problem: what is a procedure? opaque?
   • if yes: how can explain refusal, reflection on meaning?
   • if no: how different from regular representation?
2. Option2: network based representations. concept = nodes, links = relationships. facilitate certain type of inferences (inheritance, propagation). intuitive.
3. Option3: logic based representation. Compositionality principle (Frege 1890, Montague).

Use of knowledge

   "City officials refused the demonstrators a permit because"
   --- they feared violence
   --- they advocated violence

   --- Excuse me, do you know if there's a bank hapoalim near here?
   --- Today is Monday!

   Can you pass the salt?
   It's rather cold!

Generation

• Must be easily obtainable from existing systems (-> simple)
• Must be sufficient to determine text production (-> complex)

• Same content, different phrasings. Explain why. [Paraphrasing]

• Process of decision making
• Content vs. Form
• Content: selection, organization, aggregation
• Form: lexicalization, grammaticalization, morphology, linearization

• Deal with different types of knowledge (linguistic vs. non-ling)
• Simpler engineering - reusable tools

• pronominalization - choice of one-anaphora
• NP planning: definite vs. indefinite.