Separate is the opposite of Join. Join is related to Bring. Bring is related to Introduce. 
Use is a type of Act. Act is a synonym of Law. Law is related to Judicial. 
Separate <--Antonym--> Join <--RelatedTo--> Bring <--RelatedTo--> Introduce 
Use --IsA--> Act <--Synonym--> Law <--RelatedTo--> Judicial 