We study the core fragment of the Elog wrapping language used in the Lixto system (a visual wrapper generator) and formally
compare Elog to other wrapping languages proposed in the literature.
This is the second part of the long version of work first presented in the extended abstract [16], which appeared in Proc.
21st ACM SIGMOD-SIGACT-SIGART Symposium on Principles of Database Systems (PODSSemi-structured data 2002), Madison, Wisconsin,
ACM Press, New York, USA, pp. 17 – 28. The first part [18] studies the expressive power of monadic datalog over trees and
establishes the connection to the monadic fragment of the visual wrapper language Elog. The topic of the present second part
– this paper – is to study and compare Elog to other practical visual wrapper languages. This research was supported by the
Austrian Science Fund (FWF) under project No. I47-N04 Query Induction for Visual Web Data Extraction.