1. A computer-implemented conceptual network generating system that generates a conceptual network showing conceptual relations between words, the conceptual network generating system comprising: a first searching unit that searches a knowledge source storing search sentences, using as a search query first and second words conceptually related to each other, and retrieves a first search result sentence containing the first and second words; a first generating unit that analyzes the retrieved first search result sentence, and generates first structure information indicating words contained in the first search result sentence and a structure of the first search result sentence; a holding unit that stores the generated first structure information in a memory unit; a second searching unit that searches the knowledge source, using the first word as a search query, and retrieves a second search result sentence containing the first word; a second generating unit that analyzes the retrieved second search result sentence, and generates second structure information indicating words contained in the second search result sentence and a structure of the second search result sentence; a calculating unit that calculates similarity between the generated second structure information and the stored first structure information; and a setting unit that generates conceptual network information, based on the generated first structure information and second structure information having a similarity value equal to or larger than a first predetermined value with respect to the first structure information, the conceptual network information showing a conceptual relation between the first word and a third word contained in the second search result sentence corresponding to the second structure information, the conceptual relation between third word and the first word being equivalent to a conceptual relation between the second word and the first word.
1. A computer-implemented conceptual network generating system that generates a conceptual network showing conceptual relations between words, the conceptual network generating system comprising: a first searching unit that searches a knowledge source storing search sentences, using as a search query first and second words conceptually related to each other, and retrieves a first search result sentence containing the first and second words; a first generating unit that analyzes the retrieved first search result sentence, and generates first structure information indicating words contained in the first search result sentence and a structure of the first search result sentence; a holding unit that stores the generated first structure information in a memory unit; a second searching unit that searches the knowledge source, using the first word as a search query, and retrieves a second search result sentence containing the first word; a second generating unit that analyzes the retrieved second search result sentence, and generates second structure information indicating words contained in the second search result sentence and a structure of the second search result sentence; a calculating unit that calculates similarity between the generated second structure information and the stored first structure information; and a setting unit that generates conceptual network information, based on the generated first structure information and second structure information having a similarity value equal to or larger than a first predetermined value with respect to the first structure information, the conceptual network information showing a conceptual relation between the first word and a third word contained in the second search result sentence corresponding to the second structure information, the conceptual relation between third word and the first word being equivalent to a conceptual relation between the second word and the first word. 3. The computer-implemented conceptual network generating system according to claim 1 , wherein the calculating unit has the similarity value equal to or greater than the first predetermined value, when the generated second structure information and the stored first structure information show identical structures.