Patent ID: 8655921

Claim:
A true/false decision method performed by a searching apparatus, the method comprising: accepting a search condition including a logical condition formed of a plurality of variables; creating a first diagram from the search condition by using a Binary Decision Diagrams method, the first diagram storing a combination of a starting-point variable, an arrival variable and a bit which indicates true or false of the starting-point variable, the arrival variable being at a next level from the starting variable; creating a second diagram from the first diagram, the second diagram storing a combination of a starting-point variable, an arrival variable and a bit string, one or more variables being between the starting-point variable and the arrival variable, each bit included in the bit string indicating true or false of one of the one or more variables and the starting-point variable, and the bit string indicating true or false of the one or more variables and the starting-point variable; adding, to the second diagram, an uncertain logical variable to be set at a state selected between a state in which a logical value of a variable has been found and a state in which a logical value of a variable has not been found; and making a true/false decision on the search condition of a logical bit string of search target data, each bit of the logical bit string indicating true or false decision result of a variable included in the search target data, by extracting a bit string of a predetermined number of digits from the starting-point variable from the logical bit string of the search target data, and specifying the arrival variable as a transition destination based on the second diagram, wherein in the making a true/false decision, as a result of specifying the arrival variable as a transition destination, when a logical value of a variable corresponding to the uncertain logic variable is required, the logical value of the variable being required is calculated, and the uncertain logical variable is set at the state in which the logical value has been found.