Constrains ExprX and ExprY to be equal. Also constrains all variables appearing in ExprX and ExprY to be domain variables and checks that all constants and ground sub-expressions are integers.
ConsistencyModule is the optional module specification to give the consistency level for the propagation for this constraint: gfd_bc for bounds consistency, and gfd_gac for domain (generalised arc) consistency. Note that some operators (integer division, modulus) only support bounds consistency and will be propagated with bounds consistency even when posted with gfd_gac.
This constraint is implemented using Gecode's MiniModel's rel() for both integer and boolean expressions, with sub-expressions/constraints not supported by MiniModel factored out and posted as auxiliary constraints.
A more restricted version of this constraint is defined in the global constraint catalog as 'eq'. Here the constraint is defined between two domain variables rather than two expressions.
[eclipse 28]: A :: [1,3,5,7], A #= B.
A = A{[1, 3, 5, 7]}
B = B{[1 .. 7]}
[eclipse 29]: A :: [1,3,5,7], gfd_gac: (A #= B).
A = A{[1, 3, 5, 7]}
B = B{[1, 3, 5, 7]}
[eclipse 30]: A :: [1,3,5,7], gfd_gac: ( A #= B + 1).
A = A{[1, 3, 5, 7]}
B = B{[0, 2, 4, 6]}