you are likely to find Tank in/at/on War. Tank is related to Military. you are likely to find Captain in/at/on Military. Captain is a synonym of Supervisor. 
Exist is a type of Software. Mail is a type of Software. 
War <--AtLocation-- Tank <--RelatedTo--> Military <--AtLocation-- Captain <--Synonym--> Supervisor 
Exist --IsA--> Software <--IsA-- Mail 