From reistad@brokaw.lcs.mit.edu () Wed Nov 13 16:53:42 1991
Return-Path: <reistad@brokaw.lcs.mit.edu>
Date: Wed, 13 Nov 91 14:20:04 EST
From: reistad@brokaw.lcs.mit.edu ("Brian Reistad")
To: 6001-staff@ai.mit.edu
Subject: ps7 comments



Some comments on PS7 that I mentioned in staff meeting:

1.  Solutions and problem descriptions were not robust.  I.e. they did
	not specify that infinite streams were assumed or handle finite
	streams.  This was something I tried to stress to my students.
	Considering all possible 'legal' inputs to a program to generate
	a good test suite also lets the student think about what their
	program needs to do.  Assumptions are fine if listed.

2.  The specification of problem 10 did not state that the sum of the
	first n elements and the remaining stream were to be joined
	with cons, but problem 11 assumes this in second let statement.
	It would be better to use abstract selectors (Captain Abstraction)
	in problem 11 and require the student to write these in problem
	10.  Many students punted using first and just recursively called
	set-up-sums.  Wether this had anything to do with car/cdr or
	not, I'm not sure.


--Brian



