The roadmap for DebGraph outlines three sets of graph operators: essential, useful, and exotic. Naturally, each successive set extends the previous set's functionality, and in many cases the complexity of the work performed by the operators increases accordingly.

Over the weekend, I wrapped up work on the essential operators and separated the unit test suite into its own subdirectory and executable. Having a few simple operators around means that we can do basic queries:

• Show me all 3dchess packages.
  
• Show me all all libc6 packages.
  
• Show me the union of the two previous results, including dependencies between the two groups.
  

(Click the graphs for a larger version.)

These graphs can be helpful, but they are rather trivial. More useful would be an operator that could, say, find all dependency loops (cycles) and return them in such a way that each cycle could be examined individually.

Next step: an operator that computes all dependencies for a given package.