dpkg package descriptions and operation of apt and dselect

["rj-cole" <richard.j.cole@gmail.com>]

Hi,

I'm trying to write some software to visualise conflicts that arise
between packages in debian unstable. As a first step I'm trying to
understand the debian package descriptions in
/var/lib/dpkg/{available,status}. An I have some questions:

1. What is a good source for an explaination of package dependencies
and the actions of dselect and apt-get. So far I've only found the man
pages for dpkg, dselect, and apt-get and the debian policy manual.

2. Looking at my system (visible in the status file) I see that I have
installed gs-common 0.3.7, and gs-gpl 8.01-5, now gs-common conflicts
with 'gs (<< 6.51)' but gs-gpl provides gs. So my question is: does an
expression 'gs (<< 6.51)' include the virtual package gs? So far I have
been modelling that the virtual package gs has an empty version which
comes before any other version, but that would see an expression like
'gs (<< 6.51)' match a package 'gs'. What about if a package depends on
'gs (<< 6.51)' would that be satisfied by a package that provided gs?

3. Has anyone tried to formally describe package dependencies in in
debian and the rules under which a package may or may not be installed?

regards,

Richard.