上泽充通大 SJTU School Of Software 2009-2-3 2.2 Facts About Testing ◆( Question "does program P obey specification S”is undecidable！ Every testing technique embodies some compromise between accuracy and computational cost ◆Facts Inaccuracy is not a limitation of the technique It is theoretically impossible to devise a completely accurate technique Every practical technique must sacrifice accuracy in some way 软件学院SJTU School Of Software 2009-2-3 软件学院 2.2 Facts About Testing ‹ Question “does program P obey specification S” is undecidable! ‹ Every testing technique embodies some compromise between accuracy and computational cost ‹ Facts – Inaccuracy is not a limitation of the technique – It is theoretically impossible to devise a completely accurate technique – Every practical technique must sacrifice accuracy in some way