Serve is a type of Spend. Money would make you want to Spend. Money is related to Note. Note can be used for Harmony. 
Aids is a type of Virus. Virus can cause/lead to Infection. Infection is a type of Disease. Disease is related to Condition. 
Serve --IsA--> Spend <--CausesDesire-- Money <--RelatedTo--> Note --UsedFor--> Harmony 
Aids --IsA--> Virus --Causes--> Infection --IsA--> Disease <--RelatedTo--> Condition 