There are those rarer occasions when another player doubles against a bust card and ends up with a stiff hand and offers to surrender the hand to you. And other times when you offer to take half the action on split 88s against a 7 or less. Or even doubling down on his Ten against 7-8? Are the math of these various plays discussed in Carlson's BJFB 4th ed. under 'opportunistic betting'?