“…9 For example, when there is a change in the return type of a pure virtual method, the rows in which G or I appear cannot be investigated since neither the abstract class 11 can be instantiated as an object (G) nor the pure virtual method can be invoked (I). For each row, the appropriate Boolean expression is derived and reduced, if possible, 13 and the term "L" is appended if there is local impact. For example, for a deletion of a non-abstract class in the class inheritance structure (code change from "class c2: c1, 15 c0 {: : : }" to "class c2: c0 {: : : }"), the corresponding expression is H + F+L which implies there is impact in derived classes (H), in friend classes (F) and locally (L) 17 too.…”