A computer program product stored in a non-transitory computer readable medium for causing a computer to execute information processing for providing a terminal device with recommendation information relating to an item to be recommended, the information processing comprising:
- a step of receiving usage information comprising a usage subject identifier for identifying a usage subject and an item identifier for identifying an item used by the usage subject, the usage subject being the terminal device or a user who uses the terminal device;
- a step of storing a plurality of received usage information in a usage information storage section;
- a step of storing attribute correspondence information in which the item identifier and an attribute identifier for identifying an attribute of the item are associated with each other in an item information storage section;
- a step of reading the usage information stored in the usage information storage section and the attribute correspondence information stored in the item information storage section;
- a step of creating first and second aggregates, the first aggregate being an aggregate of the usage subject identifier identifying a usage subject that used a predetermined item, the second aggregate being an aggregate of the usage subject identifier identifying a usage subject that used any item corresponding to a predetermined attribute identifier;
- a step of calculating an attribute relevant degree indicating a relevant degree between the item identifier and the attribute identifier based on the first and second aggregates;
- a step of selecting two or more attribute identifiers in a descending order of the attribute relevant degree, based on the calculated attribute relevant degree;
- a step of creating relevant attribute information in which each item identifier and a relevant attribute identifier which is the selected attribute identifier are associated with each other, wherein the attribute information comprises an attribute type identifier for uniquely identifying a type of an item attribute and a name of a type of the item attribute associated with other attribute identifier, and resolved in a table format;
- a step of storing the created relevant attribute information in a relevant attribute information storage section;
- a step of specifying two or more relevant attribute identifiers corresponding to a reference item identifier, the reference item identifier being the item identifier included in the relevant attribute information stored in the relevant attribute information storage section;
- a step of specifying attribute correspondence information which has an attribute identifier coinciding with the reference item identifier from among the attribute correspondence information stored in the item information storage section;
- a step of extracting an aggregate of the item identifiers included in the specified attribute correspondence information as an aggregate of relevant candidate items;
- a step of selecting at least a part of the item identifiers as relevant item identifiers from among the aggregate of relevant candidate items;
- a step of associating the reference item identifier and the relevant item identifiers, and storing the associated identifiers in a relevant item information storage section;
- a step of receiving a relevant item acquisition request including an item identifier that is a reference of the recommendation information;
- a step of specifying a reference item identifier coinciding with the item identifier included in the received relevant item acquisition request with reference to the relevant item information storage section;
- a step of creating the recommendation information relating to the relevant item identifiers corresponding to the specified reference item identifier;
- and
- a step of transmitting the created recommendation information to the terminal device.