🚀 go-pugleaf

Hi there

I am a TA for a course in AI Programming at the University of Pittsburgh.
We are (for the first time may I add) teaching the people Prolog in this
course. We will be using Sicstus Prolog 0.7.

One of the assignments concerns modifying the WARPLAN code that is in 

  Readings in planning, edited by James Allen, James Hendler and Austin Tate,
  ISBN 1-55860-130-9, Morgan Kaufmann, 1990

The code I copied is from the paper "Extract for APIC Studies in Data 
Processing" by D H D Warren (pp 140-153). The code there is very clear 
but I am having diffculty deciding what one of the built in predicates does .
This is the "check" predicate which is shown on line 61 and 78 of the program.
Could anybody tell me what this is about ? 

And if you know where I can get the report

Warren DHD (1974) "WARPLAN : A system for Generating Plans", Dept. of 
Computational Logic Memo 76, Artificial Intelligence, Edinburgh University.

in an ftp-able format.

If someone has a Prolog implementation of WARPLAN that he/she could part with
could you e-mail it to me ?

Of course my Prof wanted this yesterday !!

Anandeep Pannu