Your Wish is My Command

5.3 The HyQL Query Language 91

The typical reason for such a failure is the modification of the site's layout or

structure. This often makes useless the information extraction procedure

that was stored in the database characterization for this particular site.

The traditional approach of dealing with this kind of problem has at

least two drawbacks:

The user will be frustrated because the agent will not produce the

desired outcome but instead an error message, at best (unless alterna-

tive sites that have not changed recently can provide the same

information).

The expert in charge of maintaining ...