
exclude(?Var, ++Excl)

   Exclude the element Excl from the domain of Var.

Arguments
   Var                 (Domain) variable or integer
   Excl                Integer value to exclude

Type
   library(gfd)

Description

   This predicate is mainly provided for compatibility with IC solver.
   If you want to remove multiple values from the domain of one or 
   more variables, it is more efficient to use the lib(gfd) specific 
   gfd_vars_exclude/2.

   Primitive for excluding an element from the domain of a variable.
   The call may fail (when Var is the same integer as Excl),
   succeed (possibly updating the variable's domain), or instantiate the
   variable (when Excl was one of only two domain elements left).

   Note that this predicate is intended for use only in implementing
   co-operation with other solvers and constraint propagators at the
   ECLiPSe level, and should not be called from ordinary user code.
   It differs from the usual constraint in that the propagation is not
   performed immediately. Normally, propagation in gecode is performed by
   a suspended goal that is scheduled and woken after each constraint is
   posted.  However, exclude/2 does not call the woken goal
   scheduler (wake/0), so the propagation goal may not be executed 
   immediately. (It is possible that under some circumstances the goal 
   will be executed, if wake/0 is called indirectly - one example would be
   by the unify handler if the variable becomes ground - but this should not
   be relied upon.) To ensure that the goals are eventually executed, the 
   caller should arrange for wake/0 to be called at some appropriate point 
   in the subsequent execution.  Please see the "Advanced Control Features" 
   section of the User Manual for more information about woken goal 
   management.



See Also
   exclude_range / 3, impose_min / 2, impose_max / 2, impose_domain / 2
