joshu wrote:

  opportunity = preparation - luck ?

I think you missed a -1 on one side of the equation. :P

Opp = Luck - Prep actually makes a bit of sense... it's the fortunate event component without the taking-advantage-of-it component.

heh, that equation doesn't hold up commutatively, apparently :)

I take it luck is more than the sum of its parts

Can you not math? Opportunity is luck minus preparation.