Understanding

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

Thematic Role Systems

Analysis

“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

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