DEVICE FOR PROVIDING GRAPHICAL INTERFACE FOR ASSISTING PREPARATION OF LOGIC FORMULA

PROBLEM TO BE SOLVED: To facilitate the preparation of a logic formula for retrieving data.SOLUTION: The device has: terms; means for storing a logic character string consisting of the combination of subexpression character strings in which the terms are combined by the logic operator; means for dividing the logic character string into the terms or dividing the terms as a subexpression tree consisting of the recursive structure of the subexpression tree in which the terms are combined by the logic operator; and number-of-cases storage means for storing the number of cases retrieved by the subexpression character string. Further, the device has display means for displaying the subexpression character string and the subexpression tree accompanied with the stored number of cases in the number-of-cases storage means, and includes means for selecting whether the subexpression tree is not displayed with the subexpression character string left as it is or whether the subexpression tree is displayed together with the subexpression character string. The user of the device can easily grasp the hierarchic structure of the logic formula, and can recognize the number of cases, and can edit the subexpression character string and the subexpression tree displayed by the display means. The device further includes means for retaining the input subexpression character string as a hysteresis.