Sale is related to Big. Big is similar to Important. Important is related to Principal. Principal is related to Leadership. 
Required is related to Assemble. Assemble is a synonym of Compound. Compound is a synonym of Prison. 
Sale <--RelatedTo--> Big <--SimilarTo--> Important <--RelatedTo--> Principal <--RelatedTo--> Leadership 
Required <--RelatedTo--> Assemble <--Synonym--> Compound <--Synonym--> Prison 