The authors would like to acknowledge the support provided

design loop, which covers a large number of design steps (called synthesis loop in figure 1). Therefore, a single cycle of the design loop is quite expensive to perform. Our approach to face this problem is to cut the design loop on a high level of abstraction by integrating a high-level estimation step. This results in a design loop which is tight and settled on high level of abstraction (called estimation loop in figure 1). For this, the evaluation of an optimization step can be done efficiently. Nevertheless, an exhaustive exploration of the design space leads to unacceptable high effort of the exploration process. This paper concentrates on algorithmic approaches on controlling the selection and application of transformations, which allows an effective exploration of the design space in an automated fashion. The paper is organized as follows: After a look at th