Towel is a type of Wipe. you are likely to find Towel in/at/on Roof. Roof is related to Sky. 
Square is related to Level. Level is related to Straight. Straighten is derived from Straight. Extend is a type of Straighten. 
Wipe <--IsA-- Towel --AtLocation--> Roof <--RelatedTo--> Sky 
Square <--RelatedTo--> Level <--RelatedTo--> Straight <--DerivedFrom-- Straighten <--IsA-- Extend 