The constrained array type allows constrained variables to index arrays, providing a rich syntax for describing CSPs. For example, given the variable var_i, with domain [0..5], the user can create an array of exponents and use it to make a constraint:
Decider examines the contents of each constraint ahead of search and makes a list of the support variables. This is used when checking constraint consistency: if no changes to variables that support a constraint have been made, the constraint does not need to be checked.
Before the implementation of MetaExpressions, the above constraint parsing would look at constraint (defined above) and rule that the implicit expression created by indexing exponentArray is the only variable that needs to be tracked. This is incorrect. The var_i variable needs to be tracked as well, which the introduction of MetaExpressions now does.
The constrained array type allows constrained variables to index arrays, providing a rich syntax for describing CSPs. For example, given the variable var_i, with domain [0..5], the user can create an array of exponents and use it to make a constraint:
Decider examines the contents of each constraint ahead of search and makes a list of the support variables. This is used when checking constraint consistency: if no changes to variables that support a constraint have been made, the constraint does not need to be checked.
Before the implementation of MetaExpressions, the above constraint parsing would look at
constraint(defined above) and rule that the implicit expression created by indexingexponentArrayis the only variable that needs to be tracked. This is incorrect. Thevar_ivariable needs to be tracked as well, which the introduction of MetaExpressions now does.