Constraint is related to Limit. Cap is a type of Limit. 
Occur is a synonym of Appear. Appear is a synonym of Arise. Open is a type of Arise. Lock can Open. 
Constraint <--RelatedTo--> Limit <--IsA-- Cap 
Occur <--Synonym--> Appear <--Synonym--> Arise <--IsA-- Open <--CapableOf-- Lock 