Homework #4
CPSC 420h - Spring 2006
due: Wed, April 26, 2006

1. Using the formalism of Event Calculus (pp. 334-340 in textbook), describe
the following information in logic:

 There was a football game last Saturday at Kyle field.
 The opponents were the Aggies (the home team) and Longhorns.
 The game began with a kickoff.
 The Aggies scored a touchdown on their first possession.
 The score was tied at (throughout) halftime.
 During half time, a band played (a "half time show").
 The Aggies intercepted the ball during the second half.
 Before the interception, the Longhorns were driving inside the 10-yard line.
 The final score was 35 to 10 (the Aggies won, of course).
 The game lasted 3 and a half hours.
 There was no overtime.

Please use the general predicates given in the book, like SubEvent(), Start(),
E(), and T() and Before().  Define the intended interpretation of each
problem-specific constant, funtion, or predicate you introduce.  Be careful
(and consistent) about how you use terms; be precise about whether they are
events, event-types, intervals, processes, moments, or fluents.

2. Describe the following process using Situation Calculus:

 To print a document in a computer, the printer and computer must be on and
 connected.  The printer must have enough paper in it.  (You may ignore toner).
 Assume that right-clicking on the document simply causes it to be printed.
 The computer may be turned on by flipping its switch, and the same for the
 printer.

From an initial state in which a 10-page phone-list is on a compter connected
to a printer with 20 sheets of paper in it, where the computer is on but the
printer is not, show that it is possible for the phone-list to be printed.
Obviously, this will require 2 steps: turn_on(printer) followed by
right_click(phone_list).  Do the proof by making a knowledge base of the
effects/frame axioms for the actions and facts representing the initial state.
Then construct a query representing the fact that the phone list would be
printed in some hypothetical situation, where you can take advantage of
omnisciently knowing the necessary sequence of actions, and show this query
can be derived from the knowledge base using first-order rules of inference.