I don't have real work I need prolog for, but I find it an interesting subject, My personal learning goal, the point where I can say I know prolog reasonably well is when I can get it to solve this mit puzzle I found, a sort of variant of soduku. I found a clever prolog solver for soduku that I thought could teach me more in this domain, but it was almost to clever, super optimized for soduku(it exploited geometric features to build it's relationships) and I was still left with no idea on how to build the more generic relationships I need for my puzzle(specific example if soduku cells were not in a grid how could they be specified?), in fact I can find very little information on how to specify moderately complex, ad hoc relationships. One that particularly flummoxed me was that some rules(but you don't know which) are wrong.