7. The document analysis system according to claim 5 , wherein, assuming that, with regard to the plurality of texts, respective sets each including one or more text are set as a respective cluster, the processor performing control for clustering so that subsequent processing is repeated until a predetermined termination condition is satisfied: to calculate each similarity degree between the clusters based each similarity degree between the each texts included in the each clusters; to select two clusters based on the similarity degree between the clusters; to merge the selected two clusters and included two texts of the selected two clusters; and to determine, with regard to the two clusters, whether or not the two clusters are to be set as the Kolmogorov complexity calculation objects based on the common character strings between the respective texts included in the clusters, wherein, when the two clusters include the Kolmogorov complexity calculation objects, the processor calculates the similarity degree of Kolmogorov complexity between the two clusters, based first merged text included in one cluster in order and second merged text included in another cluster in order, wherein, when the two clusters are not to be set as the Kolmogorov complexity calculation objects, the processor sets the similarity degree between the two clusters to zero, and wherein the processor outputs the each similarity degree of final clusters to at least one of the output device and the storage unit.
5. The document analysis system according to claim 4 , wherein the processor extracts only the common character string that does not include a predetermined exception character.