I've implemented something like this before. I ran into a lot of performance issues though. A match against a known person seems quite fast, but when you multip

I've implemented something like this before. I ran into a lot of performance issues though. A match against a known person seems quite fast, but when you multiply this against even a medium sized network of people the speed becomes problematic. This was in the 90s though, I'm sure it's much faster now - I just dont know if it's fast enough to be useful.