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sbds_try(?Var, ++Val)
tries to assign a variable to a value
- Var
- SBDS Variable
- Val
- Value to try and assign to Value
Description
Called for each variable, value pair tried at a decision point during search.
Initally tries to assign a variable to a value, if this is succesful then it updates the symmetry functions to take account of any symmetries which have been broken by this assignment.
If this assignment is unsuccesful then it stipulates that the variable cannot be assigned to this value, before placing constraints to eliminate the symmetrical equivalent of this assgnment. If these symmetries are not already broken
Exceptions
- (abort)
- Var is not an sbds attributed variable
Examples
Replacement for labeling/1 which takes SBDS into account
- sbds_labeling(AllVars) :-
- ( foreach(Var, AllVars) do
- count_backtracks,
- sbds_indomain(Var)
- ).
Replacement for indomain/1 which takes SBDS into account.
- % value ordering is input order
- sbds_indomain(X) :-
- nonvar(X).
- sbds_indomain(X) :-
- var(X),
- mindomain(X, LWB),
- %sbds_try called here
- sbds_try(X, LWB),
- sbds_indomain(X).
See Also
sbds_initialise / 4, sbds_initialise / 5, ic : search / 6