| 摘要 |
PURPOSE:To confirm whether or not a program normally operates by analyzing the program written in the page description language by type inference and verifying whether or not the program is correctly described. CONSTITUTION:A verifying means 12 analyzes the program 111 written in the page description language by using the type inference to verify whether or not the program is correctly described. Many errors of the program 111 described in the page description language can, therefore, be detected. In this mode, the verifying means 12 performs the type inference by using an axiom as to an instruction definition part included in the program 111, derive a theorem for determining the types of instructions defined by the instruction definition part from the used axiom, and registers it so that the theorem will be used for subsequent verification (121). Therefore, the theorem is used to easily perform verification regarding the execution of defined instructions. Consequently, a page printer and a display processor are prevented from being used unnecessarily. |
