[Boost-users] [BGL] edge() function also inside AdjacencyList-concept?

Hi, I was wondering that the edge()-function (to see if there is an edge between two vertices and if so also return it) also exists for the AdjacenyList- concept?! As in the documentation, I find it only under "AdjacencyMatrix refines Graph" but nowhere else. Where is it defined and what is it's time complexity (just to make sure that my assumptions on the complexity are correct) please? Best regards, Cedric