14. The processing device according to claim 5 , wherein the keyword is the name of a category contained in the hierarchical structure, and further comprising: a determination code configured to determine whether the position in the hierarchical structure of a category of which the name is given by the keyword coincides with the identified position.
5. The processing device according to claim 1 , wherein given a first search query containing keywords, the search device searches for an object that is matched with all of the keywords, the acquisition code is configured to acquire, for each category contained in the hierarchical structure, first frequencies of the name of the category and the keywords co-occurring in the first search query given to the search device, when at least a part of the distribution of the acquired first frequencies in the hierarchical structure is in conformity with a second distribution pattern that is one of the at least one distribution pattern, the identification code is configured to identify the position in the hierarchical structure of a category of which the name is given by the keyword based on the conformed part in the hierarchical structure and the position pre-associated with the second distribution pattern, and the second distribution pattern is a distribution pattern in which frequencies are all higher than a frequency presenting the absence of co-occurrence with reference to a given comparison criterion, and is pre-associated with the position immediately below the frequency at the end in the sequence of the frequencies.