Bad is a form of Bid. Bad is related to Mistake. 
Mail is related to Note. Note is related to Useful. Useful is related to Can. Can is related to Rule. 
Bid <--FormOf-- Bad <--RelatedTo--> Mistake 
Mail <--RelatedTo--> Note <--RelatedTo--> Useful <--RelatedTo--> Can <--RelatedTo--> Rule 