Alternatives explosion

Dependencies and conflicts can cumbersome with an
increasing number alternatives for a package: everytime
a new alternative was introduced all packages
referencing it needed to be updated.

An example:

Assume sendmail, postfix and exim are the only MTAs
available. Mutt and other mail user software will then
have to use a dependency like this:

     Package: mutt
     Depends: sendmail | postfix | exim