Is there a way to abort an algorithm while it's processing? Can I throw an exception out of a visitor method? I have a case where I need the algorithm to crunch on a large graph until some condition dependent on property data is reached. If and when the condition is met, I would like to skip the processing of the remaining vertices/edges and save the cycles. Does using exceptions sound like a reasonable approach? - Thanks Chris P.S. Thanks for the help with properties and property maps the other day. I cleaned up my code and eventually tracked the source of my considerable confusion to a bug in an operator= defined on the object that I'm using as an internal property. This bug manifested itself by re-initializing previously set data seemingly at random >8|-~ Arg... My bad.