String is a type of Fiber. Fiber is related to Hay. Hay is related to Food. Food is related to Rice. 
Activity is related to Point. Point is related to Theme. Statement is a type of Theme. 
String --IsA--> Fiber <--RelatedTo--> Hay <--RelatedTo--> Food <--RelatedTo--> Rice 
Activity <--RelatedTo--> Point <--RelatedTo--> Theme <--IsA-- Statement 