Complete Rules

A recursive definition (or program) must have two parts:

If the problem is easy, solve it immediately.
If the problem can't be solved immediately, divide it into smaller problems, then:
- Solve the smaller problems by applying this procedure to each of them.

Fibonacci Series
N	1	2	3	4	5	6	7	8	9	10
fib(N)	1	1	2	3	5	8	13	21	34	55

Here is an expanded version of fib(N):

fib(  ) =        (base case)

fib(  ) =        (base case)

fib( N ) = fib( N-1 ) + fib( N-2 )

The rule seems to be plagued with blanks. Can you fill them?