This monograph presents a new declarative approach dedicated to the analysis of behaviors and synthesis of structures of Systems of Cyclic Concurrent Multimodal Processes (SCCMP). These kinds of problems are some of the most difficult cyclic scheduling problems - both from the computational side and the complexity of the models used. SCCMP is understood as a set of processes (in particular, multimodal processes) that execute operations cyclically on a set of jointly used (shared) resources (processors, machines, means of transport, etc.). They model the functioning of numerous systems encountered in practical settings and which are characterized by cyclic (periodic) behavior. Typical examples are the passenger railway system, the manufacturing system, the transportation system, and etc. Considered problems, i.e., the behavior analysis problem, the structure prototyping problem, and the problem of mutual reachability of various SCCMP behaviors, are strongly NP-hard. Thisfeature implies that computationally-efficient algorithms need to be sought. They would enable the evaluation of selected aspects of the considered system's functions, such as service costs, transport time, etc., in real-time mode. In that context, the presented monograph fills the gap in the field of SCCMP modeling. Its aim is to present declarative models of systems of cyclic multimodal processes. Such models allow the development of computationally-efficient methods of analysis of the behavior and synthesis of the structure of SCCMP. The particular issues raised in this study concern: · Modeling of SCCMP with regular/fractal structures, i.e., structures composed of repeating fragments. · Determining the conditions of mutual reachability of various SCCMP behaviors. · Modeling of SCCMP described by fuzzy variables. The monograph is addressed to researchers, practitioners, and graduate students in operations management, operations research, computer science, and industrial engineering. Declarative models of concurrent cyclic processes will serve as an essential reference for professionals working on cyclic scheduling problems in computer science, manufacturing, communication, and transportation services, as well as in many other areas.