Hey people, I'd appreciate some help here: I'm trying to build up a pldb/db which starts with some precedence relations between tasks and fills in the blanks. How can I write a relational function that identifies which tasks do not have a precedence relation with every other task? Here's some example code: [precedence-db](https://gist.github.com/daveduthie/f91dc1c9587daacbba50f6b656bb8cab)

Anyone?

you need to use, uh, there should be some negation of a goal operator, not sure what it is

instead of a disequality constraint

so you have a search for the join of tasks of precedences, and then search for the tasks where that search doesn't have any results