two questions

I am having two questions about psql:

1. How to define a relation with an attribute which takes set values?
    Not really sure what you mean....

  eg. I would like to define a table like
       create table emp (name  text, tele  Set(string));  -- it does
               not work
       One tuple may look like 'Jerry', {83023381,83023800}
       I can not use array since an array is not a set.

2. How to populate instances to a table referring another table? An
   example:
    Create table CITIES (name  text, population  float);
    Insert into cities values ('Adelaide', 100.0);
    Create table people(name  text, live_in  CITIES);
    How to insert a tuple into people saying that 'Jerry' lives in
            Adelaide?
    I can not use
          INSERT INTO people('Jerry', 'Adelaide');
          since  live_in is not a string, it is a table named CITIES
    I am trying to use object reference of OR. Thus a reference path
        can be formed.

Jerry Liu, Australia