Core insight of FGA/ReBAC as presented by Yatish Mehta: rather than evaluating black-box per-permission logic, store relationships as tuples forming a graph and encode permissions as rules about how to traverse it. Asking 'can user U edit task T?' becomes 'is there a path from U to T in the graph under these rules?'. This enables dependency analysis, caching with invalidation, audit paths, and reverse lookups.