1. Conceptual Dependency CIS 479/579 Bruce R. Maxim UM-Dearborn

2. What is it? • Theory of how to represent the meaning of natural language sentences in a manner that: • facilitates drawing inferences from sentences • is independent of the language in which the sentences were originally written

3. CD • Sentence representations are not built out of primitives that correspond to the words used • Sentence representations are built out of conceptual primitives that can be combined to form meanings of words from a particular language

4. Example • To represent the sentence; “I gave the man a book.” R p

5. Example • ATRANS – Abstract transfer (e.g. give) • PTRANS – Physical transfer (e.g. go) • MTRANS – Mental transfer (e.g. tell) •  Arrow indicates direction of transfer •  Double arrow indicates two-way relationship • p = Past tense • o = Object case relation • R = Recipient case relation

6. Example Conceptual categories • Act = Action • PP = object or picture producer • AA = Action modifier or aide • PA = Picture modifier or aider

8. CD • The sentence dependency structures are building blocks that can be used in larger dependency structures (e.g. paragraphs or scripts) • The dependencies correspond to semantic relations among the underlying concepts

9. How does CD facilitate reasoning with knowledge? • Fewer inference rules are required than if knowledge is not broken down into primitives • Many inferences are contained in the CD representation itself • The initial representation built for a sentence may have holes in it and these holes serve to focus the program’s attention as it tries to understanding the sentence meaning

10. Arguments Against CD • It takes a long time to decompose knowledge into low level primitives • CD is a theory for representing events, so it may not do a good job of representing other types of knowledge (e.g. objects or social actions)