Embodiments generally relate to a solution to easily create a dictionary in which a character string to be extracted from a log of an apparatus is registered. In an example, a method includes extracting a first plurality of character strings from a first dictionary to determine types of the first plurality of extracted character strings, the first plurality of character strings having a common part at a part thereof, the a first dictionary including character strings extracted from a log of a first apparatus; extracting a second plurality of character strings having the common part from the log of the first apparatus to determine types of the second plurality of character strings; executing a first determination processing that includes determining whether the types of the first plurality of character strings are limited with respect to the types of the second plurality of character strings.