Deallocating linked lists of linked lists

[cis.ohio-state.edu!magnus.acs.ohio-state.edu!zaphod.mps.ohio-state.edu!uw]

Here's a good question...

I wrote a program that simulates a graph, and thus I need to have a linked
list, one of whose components is a linked list, showing on which vertices
that particular vertex is incident upon.

Well, enough of the nitty gritty.  Here is the question.  If I have a
variable that is a record, and one of the fields of the record is the head
pointer to another linked list, will it be sufficient to just deallocate the
one variable, or do I have to go inside and deallocate everthing?  Here are
my type declarations:

 type pointer is access edge;

 type edge is record
  incident_on : pointer;
  id_number   : positive;
 end record;

 type incidence_node;
 type edge_list is access incidence_node;

 type incidence_node is record
  item : edge;
  next : edge_list;
 end record;

 type vertex is record
  data      : node_item_type;
  id_number : positive;
  incidence : incidence_list;
 end record;

 type graph is access vertex;

So how would I dynamically deallocate something of type graph?

Thanks for any help.

-- 
Jason Lee   jplee@oboe.calpoly.edu   jlee@cash.busfac.calpoly.edu    Giants
e ^ i*pi + 1 = 0    The most beautiful equation in mathematics.      Magic
For all sad words of tongue and pen, the saddest are these:          Number:
     "It might have been."            John Greenleaf Whittier        150