Teaching is related to Punishment. Punishment is related to Pay. Pay is related to Price. Price is related to Exchange. 
Regret is related to Guilt. Killing can cause/lead to Guilt. 
Teaching <--RelatedTo--> Punishment <--RelatedTo--> Pay <--RelatedTo--> Price <--RelatedTo--> Exchange 
Regret <--RelatedTo--> Guilt <--Causes-- Killing 