• Use background knowledge to disambiguate between similar sounding statements with different meanings

Thematic Role Systems


“Ashok made pancakes for David with a griddle.”

Lexical analysis

  • categorize words, noun, verb, etc
    • “Ashok (noun) made (verb) pancakes for David with a griddle.”
  • noun phrase and verb phrase encompassing multiple words
    • “Ashok(noun phrase) made pancakes for David with a griddle(verb phrase)”

Semantic analysis

  • structure of the sentence like action, object, beneficiary and instrument
    • “Ashok(agent) made(verb) pancakes(thematic object) for David(beneficiary) with a griddle(instrument).”
  • Frame representation
Thematic Role:
- Verb: make
- Agent: Ashok
- Beneficiary: David
- Thematic Object: Pancakes
- Instrument: Griddle
  • capture verbs
  • Single verbs can be ambiguous

Leveraging Constraints


Constraints imposed by the language help guide meaning

Preposition Thematic Roles
by Agent, conveyance, location
for Beneficiary, duration
from Source
to Destination
with Coagent, instrument

Examples of by:

  • “That was written by Ashok” - Agent
  • “David went to NY by train” - Conveyance
  • “David stood by the statue” - Location

Individual verbs can be ambiguous

!!! 14.09 resolving ambiguity in verbs