Rackin' up a game of Eight Ball

[thezip]

Howdy, pardners!

As I was shooting some pool this evening (8-ball, specifically), I stumbled upon what I think might be an interesting little programming diversion:

Given a standard set of fifteen pool balls and a triangular rack, write an algorithm in Perl that provides for the optimal placement of balls within this rack so that adjacency between solid and striped balls is minimized for a game of Eight Ball.

Note that the "one" ball and the "eight" ball must be placed in the standard positions:

        1
       . .
      . 8 .
     . . . .
    . . . . .

... and balls 1-7 are "solids" and 9-15 are "stripes". The 8-ball should be considered irrelevant for all adjacency pairings.</updated++>

Since everyone has their own way of rackin' 'em up, I'd like to see some real data that shows once-and-for-all which is the best WTDI.

More importantly, I'd like to see specific algorithms that solve this problem and that provide for the necessary statistical analysis.

Have fun!

<update>Minor text clarifications to improve readability (thanks to Lawliet and ysth)</update>