  Information distributed through the Web keeps growing faster day by day, and
for this reason, several techniques for extracting Web data have been suggested
during last years. Often, extraction tasks are performed through so called
wrappers, procedures extracting information from Web pages, e.g. implementing
logic-based techniques. Many fields of application today require a strong
degree of robustness of wrappers, in order not to compromise assets of
information or reliability of data extracted. Unfortunately, wrappers may fail
in the task of extracting data from a Web page, if its structure changes,
sometimes even slightly, thus requiring the exploiting of new techniques to be
automatically held so as to adapt the wrapper to the new structure of the page,
in case of failure. In this work we present a novel approach of automatic
wrapper adaptation based on the measurement of similarity of trees through
improved tree edit distance matching techniques.
