generate a list of possible bnode mappings.
generate a list of possible bnode mappings. A very stupid implementation would for each bnode in g1 suggest every bnode in g2 as a mapping. Better implementations will filter the mappings by applying classification algorithm on the nodes by relating them to other edges
first graph
second graph
a ListMap mapping BNode from graph g1 to a smaller set of Bnodes from graph g2 which they should correspond to. The list map keeps an order of the nodes so as to put the nodes with the least options first.
Trait for implementations of BNode Mapping Generators. A good implementation should never leave out a correct mapping. Better implementations should return less mappings. (better implementations may also be less easy to understand.)