[Z3-zemantic] Interesting note on triple storage and the 4th column

[Paul Everitt]

http://www.phildawes.net/blog/2005/03/24/implementing-graphs-as-triple- 
ranges/

"Instead of implementing a graph as a single id in the 4th column of  
the quads table, how about implementing it as a range of triple ids.  
i.e. Each triple is given a sequential id in the 4th column when  
asserted, and the graphs are stored as (startid, endid)."

--Paul