Dear Alberto:

while looking for information on your special issue for TAPOS
on Web Databases. I ran into your very interesting WebOQL paper.
http://www.cs.toronto.edu/~mendel/papers.html
I found your NAVIGATION PATTERNS very interesting since this is a theme
on which we spent significant effort.

We are interested in writing structure-shy queries, i.e. queries
which don't have reveal the details of the schema since it is 
changing quickly or partially unknown.

We published a paper on this topic in 1994 on AQL:
An Adaptive Query Language for Object-Oriented Databases
http://www.ccs.neu.edu/home/lieber/theses-index.html

Our latest work on this topic is  about strategies:
http://www.ccs.neu.edu/research/demeter/biblio/strategies.html
Strategies are similar in nature to your navigation patterns.
While your navigation patterns are regular expressions
our strategies are general graphs which describe the 
overall topology of a navigation.
An earlier form of strategies was published in TOPLAS
and is available from:
http://www.ccs.neu.edu/research/demeter/biblio/compile-ap.html

Are you doing more work on navigation patterns?

-- Karl