Backgammon Match Play: Post-Crawford Strategy
The Crawford rule in backgammon match play states that no one may double on the first game after one or the other player's score is a point away from the predetermined winning match play total. This specific game, when the doubling cube is taken out of play, is appropriately called the Crawford game. Since the doubling cube is again allowed after the Crawford game in backgammon match play, post-Crawford strategy is taken into consideration. And post-Crawford strategy includes the free drop and the mandatory double.
The free drop is a post-Crawford strategy applied by the leading player in the match. It's coined "free" because the leader may drop or refuse a double without changing the fact that they're only a game away from deciding the match.
Let's say that at a post-Crawford game, you're leading one-away, your opponent is trailing two-away and your opponent offers the cube. If you take, you'll be playing the deciding the game and if you drop, the next game will remain to be the deciding game nonetheless. At this point, you only need to decide which of these two you want to go ahead with in backgammon match play.
So, if you feel that you're confident with winning the current game it's good to accept the double. Otherwise, it's OK to drop and play the next game to determine the match play winner once and for all. This cube offer by the other player in post-Crawford games is then called the mandatory double.
The mandatory double pertains to the action of the trailing player in a backgammon match play. This post-Crawford strategy takes into consideration the fact that a trailing player, when their opponent's a point away from winning, has nothing to lose by offering a double. Hence, it's almost obligatory to make the offer and play with the cube at two when the leading player is presented with a free drop.
Post-Crawford strategy encompasses the free drop and the mandatory double in backgammon match play. After the Crawford game, when the cube is again put back in play, the leading player is presented with a free drop situation if the other player offers the doubling cube. This offer by the trailing player is then coined as a mandatory double in match play. In these cases, the leader only needs to win one game to win the match whether or not the cube is accepted or dropped. And the trailing player has nothing to lose by offering the cube post-Crawford so it's almost obligatory to do so.