Properties can be either internal or external. An effective way to external properties is via std::map with a vertice or edge decriptor being used as the map's key. I believe this solution addresses both your questions. o a given vertice/edge need not have a property. o iterating the map is (or can be) independent of the graph. Hugues Joly wrote:

Hi, I've read most of the online documentation about the Boost Graph Library and I've tried a few examples but some questions remain unanswered:

Properties:

- Once we have a property map for vertices or edges, do we have to assign a value to each vertex (or edge) of the graph? (My preliminary tests tell me that we have to.)

- Is the graph the only mean to iterate through all the elements of a property map that it owns?

- What is the difference between a graph and a property graph: when would we choose to use a graph interface instead of a property graph?

- How can I attach a local property to an element of a subgraph and still have the original property unchanged for the corresponding element on the parent graph? (At the time beeing it seems impossible to do so.)

- How can I define a custom property within a specific namespace?

PROBLEMS:

It seems that there are compilers' limitations regarding the number of properties (and their value type) that can be attached to an adjacency_list (at least with CodeWarrior).

Thanks in advance.

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