nE.g. action BUY(e):
nRoles: buyer, seller, object, money
nConstraints: Human(buyer), SalesAgent(seller), IsObject(object), Value(money, Price(object))
nPreconditions: AT(buyer, Loc(seller)), OWNS(buyer,money), Owns(seller,object)
nEffects: ~Owns(buyer,money), ~Owns(seller,object), Owns(buyer,object), Owns(seller,money)
nDecomposition: GIVE(buyer,seller,money), GIVE(seller,buyer,object)