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# default_domain(-Var)

This predicate is called to assign a default domain to a free variable Var which occurs in arithmetic constraints.

-Var
A
  variable

## Description

This is a simple hook predicate which allows the user to modify the domain which is by default assigned to domainless variables that occur in arithmetic constraints. When such a variable is encountered, this predicate is invoked and it must give the variable an integer finite domain. To modify the default domain, it is necessary to recompile this predicate in the module fd_arith.

### Fail Conditions

None

### Resatisfiable

No.

## Examples

       [eclipse 13]: A #> B.
       A = A[-9999999..10000000]
       B = B[-10000000..9999999]
       ...
       [eclipse 14]: compile(user, fd_arith).
       default_domain(X) :- X::0..100000000.
       user       compiled traceable 56 bytes in 0.00 seconds
       yes.
       [eclipse 20]: X #> Y.
       X = X[1..100000000]
       Y = Y[0..99999999]

## See Also

new_domain_var / 1, :: / 2, #:: / 2