It is often the case that pages of considerable interest to the user are not very far from the user's current position, if only the user knew exactly which links to follow to arrive at them. Uncontrolled breadth-first search is known to be combinatorially explosive, hence impractical. In practice, though, Letizia's breadth-first search is constrained by the interactive behavior of the user. Whenever the user switches from one Web page to another, Letizia's search is immediately refocused to the new page. The user typically looks at a Web page for two or three minutes, then goes on.
Web pages tend to be approximately of uniform size.
Thus the search tends to remain manageable. This heuristic is not very reliable, but is quick to compute and serves as a placeholder for more sophisticated techniques. A user profile is accumulated during browsing, and may be written out and read back in across sessions so the user profile can be persistent. A dead end is a link that looks like it might be interesting from reading the link text or seeing a link image, but turns out not to be. A garden path is a sequence of links that provide just enough incentive to keep following the path, but ultimately results in a dead end.