In this diagram, Black resigned after White took the ko for the last move. Presumably because he could not find a large enough threat.
If White loses the ko fight, Black makes quite a bit of territory on the top.
It is unclear ( to most players ) whether or not Black lives in the corner if he loses the fight.
Bill: Black can give up the ko and live easily.
Not that that is best play, OC. ;-)
Taking into account the two scenarios: Black lives if he loses; and Black dies if he loses, can someone place a range of values on the ko fight?
Bill: Too much work for me.