MARICI implements the algorithm derived from mathematical crystal chemistry (MCC), which formulates the empirical rules of inorganic structural chemistry by mixed-integer nonlinear programming (MINLP). MINLP is an optimization problem of real and integer variables with equality and/or inequality constraints. If an integer variable is zero or one, it is called "logical variables". MCC clarifies that the set of simple rules, which includes the logical-decision problem consisting of logical variables, discovers promising prototypes of crystal structures very efficiently.