First refinement Sample Clauses
First refinement. Refinement_Plan_Requirement_1 : A relation (Train_occupancy) defines the cells occupied by each train. Refinement_Plan_Requirement_2 : A train may Appear/dissapear from Train_occupancy only if the train is located on the garage zone. Refinement_Plan_Requirement_3 : A train can change its location (by modifying Train_occupancy). Refinement_Plan_Requirement_4 : no collision: Two different trains cannot occupy the same cells at the same time.
First refinement. Two requirements describe how to model the train occupancy on the track, and how to define the "no collision" (also called safe train separation in the SRS) requirement: These two requirements are modelized as invariants: