A growing trend in modeling is the construction of high-level modeling languages that invoke a suite of solvers. This requires automatic reformulation of parts of the problem to suit different solvers, a process that typically introduces many auxiliary variables. We show how semantic typing can manage relationships between variables created by different parts of the problem. These relationships must be revealed to the solvers if efficient solution is to be possible. The key is to view variables as defined by predicates, and declaration of variables as analogous to querying a relational database that instantiates the predicates. The modeling language that results is self-documenting and self-checks for a number of modeling errors.