(Research project) Relational programming with state. In the relational computation model of this chapter, explicit state that is created outside of a relational program can only be read, not modified, during the execution of the relational program. This restriction exists because of encapsulated search (see, e.g., [188, 190]). For this exercise, investigate how to remove this restriction while maintaining the desirable properties of the relational computation model, i.e., its simple logical semantics and efficient implementation.