For Google-style page ranking, it is supposedly important to have links from one page to another. If the word "Colombia" is mentioned in the article about "Bogota" but not linked, this relationship will be missed in the ranking. One way to avoid such misses would be for a robot to take the list of article titles and search for their occurance in the text body of all articles, and insert brackets where they are missing.

No, I don't suggest that such a robot should be used in Wikipedia. For one thing, we do have articles about many common words and for every year in history, but it would not make sense to make a link for every mentioning of a year or such common words.

What I would like to ask is whether this kind of text mining is common and has a name? So this is more of a general question about information retrieval (IR) in large text corpuses than about Wikipedia. Are there arithmetic rules for when such links should be avoided?

One place where such automatic linking could be interesting is a scanned paper encyclopedia, where no links exist beforehand, e.g. http://en.wikisource.org/wiki/The_New_Student%27s_Reference_Work