3. A keyword display system according to claim 2 , wherein said emphasized display of the relevancy between the keywords is carried out by employing one of a thickness of a line indicative of the relevancy between the keywords, a distance between displaying positions of the keywords, and a color of a line indicative of the relevancy between the keywords, or a combination thereof.
6. A keyword display system according to claim 3 , wherein said keyword display controller changes the color of the line indicative of the relevancy between the keywords in such a manner that it becomes a red color as said keyword relation degree becomes larger.