Purchase is a type of Acquisition. Purchase is related to Market. 
Butt is a type of Put. Put is related to Safe. Safe is a different concept from Risky. Surgery can be Risky. 
Acquisition <--IsA-- Purchase <--RelatedTo--> Market 
Butt --IsA--> Put <--RelatedTo--> Safe <--DistinctFrom--> Risky <--HasProperty-- Surgery 