上大学2.3 What is a“good'model? SHANGHAI JIAO TONG UNIVERSITY Relationships,which are valid in reality R,are also valid in model M. I:Mapping of real things in reality R to abstractions in the model M abbildet (Interpretation) f:relationship between abstractions in M f:relationship between real things in R In a good model the following diagram is commutative: [lt preserves relationships among the objects it represents.] fu M M I R R fR Software EngineeringSoftware Engineering 2.3 What is a “good” model? Relationships, which are valid in reality R, are also valid in model M. • I : Mapping of real things in reality R to abstractions in the model M abbildet (Interpretation) • fM: relationship between abstractions in M • fR: relationship between real things in R In a good model the following diagram is commutative: [It preserves relationships among the objects it represents.] fM fR M M R R I I