Generalization hierarchy set generation apparatus, generalization hierarchy set generation method, and program

A generalization hierarchy set generation method, comprising:

• first generating a first generalization hierarchy set, that is a subset of a generalization hierarchy set, from a generalization target data set containing generalization target data as elements and the generalization hierarchy set containing generalization hierarchies as elements, wherein the generalization hierarchy set contains at least one generalization hierarchy that, for any of the generalization target data included in the generalization target data set, includes the generalization target data;
• and
• second generating a second generalization hierarchy set from the generalization target data set and the first generalization hierarchy set, wherein
• the second generating the second generalization hierarchy set from the generalization hierarchy set, which contains all elements of the generalization target data set, reduces information loss,
• provided that M is an integer equal to or greater than 1 that expresses a maximum value of a length of the generalization hierarchies included in the generalization hierarchy set,
• the first generalization hierarchy set satisfies a property such that any generalization hierarchy included in the first generalization hierarchy set includes at least one of the generalization target data included in the generalization target data set,
• for d that satisfies 0≤d≤D−1, where D is a predetermined integer equal to or greater than 1 and less than or equal to M, the first generalization hierarchy set satisfies a property such that data in a dth layer of generalization hierarchies included in the first generalization hierarchy set is the same data, and a set that contains data from a (D−1)th layer to an (M−1)th layer of the generalization hierarchies included in the first generalization hierarchy set as elements includes the generalization target data set, and
• provided that D′ is a predetermined integer equal to or greater than D and less than or equal to M, the second generalization hierarchy set satisfies a property such that a length of generalization hierarchies included in the second generalization hierarchy set is D′, and data in a (D′−1)th layer of the generalization hierarchies included in the second generalization hierarchy set is an element of the generalization target data set.

A non-transitory computer-readable storage medium which stores computer executable instructions which, when executed by a processor of a computer, cause the computer to;

• generate a first generalization hierarchy set, that is a subset of a generalization hierarchy set, from a generalization target data set containing generalization target data as elements and the generalization hierarchy set containing generalization hierarchies as elements, wherein the generalization hierarchy set contains at least one generalization hierarchy that, for any of the generalization target data included in the generalization target data set, includes the generalization target data;
• and
• generate a second generalization hierarchy set from the generalization target data set and the first generalization hierarchy set, wherein
• generation of the second generalization hierarchy set from the generalization hierarchy set, which contains all elements of the generalization target data set, reduces information loss,
• provided that M is an integer equal to or greater than 1 that expresses a maximum value of a length of the generalization hierarchies included in the generalization hierarchy set, the first generalization hierarchy set satisfies a property such that any generalization hierarchy included in the first generalization hierarchy set includes at least one of the generalization target data included in the generalization target data set,
• for d that satisfies 0≤d≤D−1, where D is a predetermined integer equal to or greater than 1 and less than or equal to M, the first generalization hierarchy set satisfies a property such that data in a dth layer of generalization hierarchies included in the first generalization hierarchy set is the same data, and a set that contains data from a (D−1)th layer to an (M−1)th layer of the generalization hierarchies included in the first generalization hierarchy set as elements includes the generalization target data set, and
• provided that D′ is a predetermined integer equal to or greater than D and less than or equal to M, the second generalization hierarchy set satisfies a property such that a length of generalization hierarchies included in the second generalization hierarchy set is D′, and data in a (D′−1)th layer of the generalization hierarchies included in the second generalization hierarchy set is an element of the generalization target data set.