[boost] [BGL] read_graphviz()/read_graphml() and subgraphs

Subject: [boost] [BGL] read_graphviz()/read_graphml() and subgraphs
From: Giuseppe Di Guglielmo (giuseppe.diguglielmo_at_[hidden])
Date: 2009-09-24 08:11:50

Dear all,
I read on the 'read_graphviz()' page in BGL library doc
http://www.boost.org/doc/libs/1_40_0/libs/graph/doc/read_graphviz.html

* read_graphviz treats subgraphs as syntactic sugar. It does not reflect
subgraphs as actual entities in the BGL. Rather, they are used to shorten
some edge definitions as well as to give a subset of all nodes or edges
certain properties. For example, the DOT graphs digraph { a -> subgraph {b
-> c} -> e } and digraph { a -> b -> e ; a -> c -> e ; b -> c} are
equivalent.

Is this actually true? Can I read sub-graph from DOT description and obtain
a subgraph object?
http://www.boost.org/doc/libs/1_40_0/libs/graph/doc/subgraph.html

Eventually are subgraph supported by 'read_graphml()' function?

http://www.boost.org/doc/libs/1_40_0/libs/graph/doc/read_graphml.html

Thanks,
G.