key subroutines

[Stuart Cracraft <cracraft@xxxxxxxxxxxxx>]

I was curious what you folks think are the key Go-type
subroutines for a GO program to have at its beginning
and how hard they are to write (likely to impossible
to semi-perfect only)

All I could think of are:

	liberties(gst) - calculates and returns number of liberties of
			 any stone st or group. Only the intersection
			 of the stone needs to be supplied. 

	eyes(g) - calculates the number of eyes of the group g and
		   returns it

	alive(g) - simply returns 'eyes(g) > 1' - returns true if group
		    has more than one eye

	group(st) - returns list of stones belonging to the same group
		    of which stone st is a member

How about others? influence()?

--Stuart