42. The computer-readable recording medium according to claim 41 , wherein the computer is further caused to execute the step of: (c) generating a plurality of the units of analysis from the text information, wherein in the step (b), the density is estimated for each unit of analysis generated in the step (c).
43. The computer-readable recording medium according to claim 42 , wherein in the step (c), the plurality of units of analysis are generated, such that a sentence included in each unit of analysis coincides with a sentence included in another unit of analysis.