Backgammon, Part 8

I’ve talked about risk, and I’ve kind of alluded to consequences, so I’d like to go a little more into what happens if a risk doesn’t pan out.

(Red-only board.)

(White-only board.)

Let’s pretend that we have two boards, one just for White and the other just for Red. Neither board has the opponent’s stones on them. Then both sides take turns rolling the dice and moving their stones to bear them off. This is a pure running game, and as mentioned before, running games are determined by who gets the most doubles and high rolls (6’s and 5’s). It’s strictly random, and there’s no skill involved. A little commonsense at the end, though, when a player chooses to jockey the stones in the home field rather than just bearing them off as soon as it’s possible. And, there’s no reason to focus on building blocks.

In a purely random game with balanced dice, the winner shouldn’t win by more than 1 or 2 stones. Plus, after 10 games the score should be 5-5, with the winner being the person that took the first turn for each game.

What this means is that in an actual game, you’re trying to overcome the randomness of the dice to make the odds of specific rolls coming up work in your favor to give you a significant advantage to increase your chances of winning. Or, in other words, you want to make the other guy take more turns than you do.

(Red gets double 6’s on the first roll: he moves to interfere with White’s 6’s.)

There are several ways to force an opponent to take extra turns, the obvious one being to send them to the bar. Another is to put blocks on the 7 and 18 points so that his options for using 6’s when they come up are more restricted. Or, just to have several blocks in a row so that some of the stones are trapped in the back field. The ultimate method, of course, is to put the opponent’s blot on the bar and then have all 6 points in your home field blocked so he can’t get back on the board.

(Red’s home field is blocked, preventing White from getting off the bar. Effectively, White loses his turn as long as this wall remains in Red’s home field.)

Actually, if we look at risk, we can see that the consequences vary depending on several factors. I talked before about the danger of hitting too many blots and filling up your home field with the enemy’s stones, as well as what happens if you hit a blot that has a chance of landing on one of your blots in your home field and putting you on the bar when your opponent’s home field is fully walled off. One more consequence, though, is that you’re effectively sacrificing turns if your blot is hit.

(Red is hit on point-24. He goes to the bar. Depending on the dice, he could get back on the board at point-24, or at point-20.)

Say you’re Red and you have a blot on point-24. If you get hit and sent to the bar, then you roll a 1, if you return to point-24 all that happened was that you gave up one die on one turn. And actually, if you roll a 5 and land on point 20, there’s no real impact to you at all – it’s the same as having decided to use a 4 on one die to move that stone from point-24 to point-20. No loss.

(Red moves 2 stones from point-13, one to point-10 and the other to point-9. White hits him on point-9 and sends him to the bar. If he returns to the board at point-24, it will take an average of three turns just to get that one stone back to point-9.)

But, say that the blot is on point-9 (it’s the start of the game, and you move from point-13 to point-9 because you got a 3-4 on the first roll). If you’re sent to the bar now, and get back on the board at point-24, it will take time to make up for that loss. It’s 15 points to go from 24 to 9. You COULD get double 6’s (2.5% chance), followed by a 1-2, to do it in 2 turns. The average is 7, meaning that it’d be closer to 3 turns. Worse, if your blot was originally on point-1, to make up the loss of 23 points could take 4 or 5 full turns.

In a pure running game, taking the risk of a blot being hit on point-9, and then having it hit and sent to the bar, is tantamount to forfeiting the game. Sure, you could get lucky and hit your opponent’s blot in return and force the same penalty on them, but if they play a safe game, your odds of being lucky will be small (about the same odds as getting high doubles two turns in  a row to play catch-up).

Taking that risk is also a signal that you intend to play a back game. If you know you’re going to get hit, then you need to force your opponent into leaving blots against their will. This is where you keep a block on point-23 or -24, and build up a wall four or five points long close to your home field. If you can completely block your home field so that your opponent can’t get back on the board, assuming you can put him on the bar, then he’ll lose several turns as you bring your farthest stones up and prepare for bearing off. Putting a block 6 points away from your opponent’s block can force him to leave a blot if he rolls a 6 plus something smaller (depending on how the rest of the board is laid out.)

Both sides are looking at making the other side give up turns, either by blocking key strategic points, or by forcing them to leave a blot closer to their home field that could be sent to the bar. Once on the bar, you don’t want them getting back off right away.

The problem with playing a back game is that if you get bad dice, your opponent won’t leave any blots open, or you won’t be able to hit them, and you could lose the game without bearing any stones off at all, which is a gammon, and doubles the value of that loss.

The bottom line is that backgammon is all about calculated risk, and understanding the consequences of those risks at different locations on the board at different stages of the game. And being prepared to lose if the risk doesn’t pay off.

To be continued.

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