9. The text processing apparatus according to claim 8 , wherein the descriptive content determination unit derives, based on the result of the determination by the segment determination unit, an extent to which the content of the homogeneous segment is included in the second text corresponding to the other first text which includes the homogeneous segment, further derives, based on the derived extent, a degree to which each segment constituting the first text which is set as the analysis target should be described in the second text corresponding to the first text which is set as the analysis target, and performs the determination using the degree.
9. The text processing apparatus according to claim 8 , wherein the descriptive content determination unit derives, based on the result of the determination by the segment determination unit, an extent to which the content of the homogeneous segment is included in the second text corresponding to the other first text which includes the homogeneous segment, further derives, based on the derived extent, a degree to which each segment constituting the first text which is set as the analysis target should be described in the second text corresponding to the first text which is set as the analysis target, and performs the determination using the degree. 10. The text processing apparatus according to claim 9 , wherein the inclusion determination unit, in addition to the determination regarding the content of each segment, computes, for the plurality of segments respectively constituting all of the first texts, an inclusion score representing a possibility of the content of each segment being included in the second text corresponding to the first text which includes the segment, and the descriptive content determination unit further derives the degree using the inclusion score computed by the inclusion determination unit, such that the degree increase the higher the inclusion score.