. In this paper, an architecture for the combination of different constraint solvers with the help of projections is proposed. By means of the definition of an interface and restricting properties of the operations of constraint solvers we are able to define a mechanism for the open and consistent combination of constraint systems. We enable the use of a functional logic language as constraint solver for constraints over functional expressions in the overall system. The syntax of a language which allows the specification of mixed constraints of different constraint domains and its operational semantics are introduced. We compare our approach with BALI, an environment for designing and executing constraint solver combinations. 1 Introduction The paradigm of constraint programming () offers efficient mechanisms to handle constraints of various constraint domains. However, one constraint solver is only able to handle constraints of one particular constraint domain. It is desirable and..