you are likely to find People in/at/on Convention. Convention is a type of Practice. 
Pass is a synonym of Authorize. Authorize is a type of Permit. Permit is related to City. City is related to Chief. 
People --AtLocation--> Convention --IsA--> Practice 
Pass <--Synonym--> Authorize --IsA--> Permit <--RelatedTo--> City <--RelatedTo--> Chief 