On Tue, 6 Aug 2002, Erik Arner wrote: yg-boo> yg-boo> OK thanks, I now realize I formulated the question wrongly. What I yg-boo> really was looking for is a fast method for determining whether two yg-boo> vertices have common *descendants*, not necessarily children... I might yg-boo> have to perform this task many times during the run of the program, so yg-boo> it really needs to be fast. Any thoughts? Yeah, what you want is the transitive closure of the reverse graph. This adds edges such that all descendants become children. Cheers, Jeremy ---------------------------------------------------------------------- Jeremy Siek http://php.indiana.edu/~jsiek/ Ph.D. Student, Indiana Univ. B'ton email: jsiek@osl.iu.edu C++ Booster (http://www.boost.org) office phone: (812) 855-3608 ----------------------------------------------------------------------