Years ago I read an article on route-finding in real time. It was something to do with routing telephone calls through exchanges. Aparrently it was sometimes taking a VERY long time to find the shortest path. Then some people (Cambridge students, if memory serves) came up with an idea. The basic algorithm was still used to start with, but after a short time, if it appeared that there were going to be many more choices, the algorithm just picked a nuumber of routes at random and chose the shortest of those. Everyone was happy, because callers weren't kept waiting while the computer (which in those days was a lot slower than we have now, but the principle still holds) trawled its way through thousands of possiblities trying to find the quickest route. And taking a l-o-o-o-n-g time finding it:-) Just thought I'd share that - someone may find it useful.. Cheers, Diolma