Two questions regarding lib(fd).

Hi,

I have looked at the "roster.ecl"-example from the ic-parc website. I have tried 
to understand what is going on but there is one confusing clause.

>From the roster.ecl:

    try_day_off(X) :- X #= r of shift.
    try_day_off(X) :- X #\= r of shift.

Why does this give sense?


The other quetion is this:

What is the difference of '#\=' and '##'? The description is the same:

  ?X #\= ?Y
  X is different from Y.
  ?X A linear term.
  ?Y A linear term.
  Desrcription:
   This constraints states that the two linear terms are not equal.  It is
   suspended until at most one variable appears in it and then its domain
   is updated so that the constraint is satisfied.

Thanks in advance.

Ole Tranberg