Post is related to Envelope. Envelope is related to Mail. Mail is related to Magazine. 
Expectation is a synonym of Trust. Trust is related to Promise. Undertake is a type of Promise. 
Post <--RelatedTo--> Envelope <--RelatedTo--> Mail <--RelatedTo--> Magazine 
Expectation <--Synonym--> Trust <--RelatedTo--> Promise <--IsA-- Undertake 