Just to address what Markus was hinting at with inference rules. Both positive and negative rules could be stored. Back in the Freebase days, we had those and were called "mutex's". We used them for "type incompatible" hints to users and stored those "type incompatible" mutex rules in the knowledge graph. (Freebase being a Type based system along with having Properties under each Type)
Such as: ORGANIZATION != SPORT
You actually have all those type incompatible mutexs in the Freebase dumps handed to you where you could start there. The biggest one was called "Big Momma Mutex".