[provenance-challenge] VisTrails OPM

[David Koop]

Our OPM output for a run of the workflow successfully generating a  
histogram has been posted and includes three overlapping accounts.  In  
the near future, we will post output for different scenarios in order  
to test different queries.  The posted images of the graphs for the  
three accounts should clarify what the VisTrails entities stored in  
the value elements for processes and artifacts represent, but let me  
know if you have any questions about parsing or understanding them.

Dave