hw2

Tim Finin (finin@cs.umbc.edu)
Wed, 05 Mar 2003 14:28:43 -0500

I'm resending this since we had a problem with email yesterday
which caused some mail sent to majordomo based mailing lists
(like 771) to be lost. 

--

if you are still floundering with this problem, try
looking at the partial solution in

    http://www.cs.umbc.edu/771/current/hw/hw2/partialsolution.P

Note: You will need to represent a list of couples paired so far
in your solution. A typical way to represent something like
this is as a Prolog list where each element is just a tuple
like john+mary.

So, you might expect to see:

  >> xsb
    [xsb_configuration loaded][sysinitrc loaded][packaging loaded]
    XSB Version 2.2 (Tsingtao) of April 20, 2000
    [i686-pc-linux-gnu; mode: optimal; engine: chat; scheduling: batched]
    | ?- [sm,people].
    [Compiling ./sm]
    [sm compiled, cpu time used: 0.1310 seconds]
    [sm loaded]
    [people loaded]
    yes

    | ?- test.
    Stable couples: [edward + carol,donald + denise,carl + eunice,bill + betty,alan + alice].
    yes

    | ?-

One key predicate you will have to write is one that takes two couples
(e.g., john+mary and bill+sue) and succeeds if they are unstable with
respect to each other. (e.g., john prefers sue to mary and at the same
time sue prefers john to bill, OR mary prefers bill over john and at the
same time bill refers mary to sue).

another predicate you will no doubt need is one which
takes a set of pairing so far (e.g., [john+mary,bill+sue])
which we know is stable, and a potential new couple (say
george+laura) and succeeds if the new couple is stable
with respect to each of the couples in the pairings
so far.

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