Sorry if I have overlooked something in the docs, but Im really not finding it... Is there someway to check the existence of an edge in adjacency_matrix in constant time knowing its vertices? An explanation or a pointer to the right place in the docs would be really appreciated. Thanks in advance, -- Felipe Magno de Almeida UIN: 2113442 email: felipe.almeida at ic unicamp br, felipe.m.almeida at gmail com, felipe at synergy com I am a C, modern C++, MFC, ODBC, Windows Services, MAPI developer from synergy, and Computer Science student from State University of Campinas(UNICAMP). To know more about: Unicamp: http://www.ic.unicamp.br Synergy: http://www.synergy.com.br current work: http://www.mintercept.com "There is no dark side of the moon really. Matter of fact it's all dark."