00100	CS 224   Models of Thought Processes
00200	
00300	Handout #7.		Homework #6.
00400	Thursday, May 9.	Due: Thursday, May 16.
00500	
00600	Do the following two problems (We strongly urge you to look
00700	at and think about the optional parts of each).
00800	
00900	1) Recall the sequence of five problems that Fikes describes near the end
01000	of his paper. Your job is to build the triangle table for problem 1
01100	and problem 2 (pages 52-53 of Classnotes). Here are details:
01200	 (a) Construct the triangle table for Problem 1.  Use the operator
01300	descriptions given on page 51, but note the following correction:
01400	for the additions after applying PUSHB(bx,by), the first clause
01500	should read *NEXTTO(bx,by), not *NEXTTO(bx,dx) as it does  currently.
01600	 (b) Lift the triangle table. Hint: replace the specific names of
01700	all the boxes, rooms, and doors by parameters; no more, no less.
01800	Be sure about which clauses do and don't get asterisks (support).
01900	 (c) Now look at problem 2. Find a row of some MACROP which matches
02000	the goals of this problem (Hint: the only existing MACROP is the one
02100	you just created). Try to apply this MACROP (satisfy some kernel).
02200	This won't quite work. Examine the first kernel (leftmost column)
02300	and decide why it isnt satisfied. Again look for a row in a MACROP
02400	which matches this difference clause. Edit the MACROP so that only
02500	those operators needed to support the desired action are included.
02600	 (d) Join the MACROP and the edited MACROP you have found in (c).
02700	 (e) Optional: If you have time, discuss some of the following:  Show
02800	how the MACROP applies to solve problem 2. Is the new MACROP completely
02900	lifted (can any of its constants be replaced by parameters)? Does this
03000	MACROP eliminate the need to keep the first MACROP around? 
03100	Explain.  Why would it have been easier for you to do the triangle 
03200	table for problem 2 from scratch, rather than using the first MACROP?
03300	Why, then, is it easier for STRIPS to use MACROPS?