Hi, I'm a student applying for GSoC to Boost Graph Library. This is my second post here and this mail is regarding the incidence matrices project for the BGL(earlier one was for hypergraphs and these are the two ideas which interested me the most in the 'ideas list'.) I have gone through the idea and the BGL documentation and the idea appeals to me as pretty interesting, useful and implementable. Also, I do not have any other commitments during the summer. I am giving a rough idea of what I understood we have to do in this project. Please correct me if I am wrong anywhere and clarify my doubts. Most of the concepts which I'm discussing here are obtained from wikipedia ( http://en.wikipedia.org/wiki/Incidence_matrix) . As far as I understand, we have to implement generic incidence matrices for: 1. oriented incidence matrices for undirected graphs. The matrix will contain zeroes and ones. 1 if the corresponding vertex and edge are incident, 0 otherwise. One edge has two incident vertices. 2. incidence matrices for directed graphs. matrix will contain 1, 0 and -1. -1 for edge coming out of vertex, +1 for edge going into vertex (or maybe the opposite convention) and 0 for edge and vertex not incident. 3. unoriented incidence matrices for undirected graphs (similar to above case). 4. Signed graphs. A method for filling up the incidence matrix is given here : http://en.wikipedia.org/wiki/Signed_graph#Incidence_matrix 5. Bidirected graphs. A convention can be made but I'm not sure yet. It would be better if you could throw some light on this topic, i.e how to get an incidence matrix of a bidirected graph. 6. Hypergraphs. Incidence matrices are a good way of representing hypergraphs and this adpatation can help a lot in implementing hypergraphs. The incidence matrix can be obtained as given here: http://en.wikipedia.org/wiki/Hypergraph#Incidence_matrix Apart from these, we can also think of using incidence matrices to get the Kirchoff Matrix and adjacency matrix (I am not sure if adjacency matrix already exists in BGL) if it is possible and time permits. Please tell me if I am going in the right direction and if there is anything I left out or included unnecessarily. Any other information regarding the project will be highly appreciated. Thanks for your reply in advance, Ciao, Om P Patri, Sophomore, Computer Science and Engineering Indian Institute of Technology, Guwahati, India. ----------------------------------------------------------------------------------------------------------- Incidence Matrices <https://svn.boost.org/trac/boost/wiki/soc2009#IncidenceMatrices> An incidence matrix (http://en.wikipedia.org/wiki/Incidence_matrix) is a graph data structure that relates vertices to the set of edges that connect them. This project would entail the implementation of a generic incidence matrix data structure that fits into the BGL generic graph interface. This project can include the development and definition of concepts related to graphs represented by incidence matrices (e.g., signed and bidirected graphs). Incidence matrices can also be adapted to implement hypergraphs.