ACTION 162 (Investigate top/bottom roles in dl-lite)

Hi Ian, hi all,

regarding the inclusion of top/bottom roles in DL-Lite, we have  
analyzed the problem and they do not constitute a problem wrt the  
computational properties of the fragment.

They introduce the need to address satisfiability of the TBox alone  
(without bottom roles, a DL-Lite TBox is always satisfiable), and  
hence to modify the query answering algorithms, but this can be taken  
into account.

- Diego