
?B isd ?C

   The constraint expression C evaluates to the boolean value B.



Arguments
   ?B                  A variable with domain 0..1.
   ?C                  An arithmetic constraint expression.

Type
   library(fd)

Description
   This is an evaluation constraint.  It states that the constraint
   expression C evaluates to the boolean value B, where the value 0 means
   false and 1 true.  This constraint can be used both to test the validity
   of the constraint expression (entailment test) and to impose this
   constraint or its negation.  For the former, B will be instantiated as
   soon as either the constraint expression or its negation is subsumed by
   the current state of its domain variables.  For the latter, when B is
   instantiated, then depending on its value, either the constraint
   expression or its negation will be imposed on its arguments.




Fail Conditions
      Fails if both C is true.



Resatisfiable
      No.

See Also
   #=> / 3, #<=> / 3, #\/ / 3, #/\ / 3, is / 2
