Speech Acts 2

Planning Questions

exists (x) Believe (Mary, (Name (Mother (John)) = x))
Knowref (Mary, x, Name (Mother (John)))

Believe (Ken, Mammal (Whale)) or Believe (Ken, not (Mammal (Whale)))
Knowif (Ken, Mammal (Whale))

Operators for asking questions

Informref (sp, hr, x, p(x))
Preconditions:
  Knowref (sp, x, p(x))
  Want (sp, Informref (sp, hr, x, p(x)))
  Channel (sp, hr)
Effect:
  Knowref (hr, x, p(x))

Informif (sp, hr, p)
Preconditions:
  Knowif (sp, p)
  Want (sp, Informif (sp, hr, p)
  Channel (sp, hr)
Effect:
  Knowif (hr, p)

Recognizing a Speaker's Plans

Knowing S's plan can aid in making useful responses
- H can execute other actions required as a part of S's plan
- H can recognize obstacles in S's plan and do something about them
- H can find errors in S's beliefs and correct them
Example: Jack: How much is a ticket for the 3:00 to Chicago? (There is no 3:00 train to Chicago; the next train leaves at 3:30.)
- Anticipated actions
```
Informref (Clerk, Jack, y, Price (Ticket (Train1)))
Give (Clerk, Jack, Ticket (Train1))
```
- Obstacles
```
Knowref (Jack, x, Price (Ticket (Train1)))
Knowref (Jack, x, Depart-Loc (Train1))
```
- Belief errors
```
Believe (Jack, (Depart-Time (Train1) = 3pm))
```
- Appropriate response: There's no 3:00 train; the next one is at 3:30. The ticket costs $50.

Indirect Speech Acts

Example: Do you know the departure gate for the train to Chicago?
3 possibilities
- S really wants to knowif the proposition.
- S has a plan that has the proposition (or its negation) as a precondition.
- S wants the proposition to be true.

Plan recognition based on the third possibility

Take-Trip (Jack, Train1, Chicago)
   decomposes to
Go-To (Jack, Depart-Loc (Train1))
   presupposes
Knowref (Jack, Depart-Loc (Train1))
   effect of
Informref (Clerk, Jack, x, Depart-Loc (Train1))
   presupposes
Believe (Jack, Knowref (Clerk, x, Depart-Loc (Train1)))
   effect of (if yes)
Knowif (Jack, Knowref (Clerk, x, Depart-Loc (Train1)))
   effect of
Informif (Clerk, Jack, Knowref (Clerk, x, Depart-Loc (Train1)))
   presupposes
Want (Clerk, 
      Informif (Clerk, Jack,
                Knowref (Clerk, x, Depart-Loc (Train1))))
   effect of
Request (Jack, Clerk,
         Informif (Clerk, Jack,
                   Knowref (Clerk, x
                            Depart-Loc (Train1))))

[L645 Syllabus]

Last modified: Wed Dec 10 11:19:29 EST
Comments: gasser@cs.indiana.edu