Doubling Cube Lesson

In the position below, it is a money game and White is on Roll. Should White double? If White doubles, should Black take or drop?

The way we “find out” whether it is right to double and then whether it is right to take or drop is to put the position into one of the two excellent computer programs, GNUBG or Snowie, and see what it says.

As you can see, I put this position into Snowie and it tells us that White should not double, and that if doubled Black should take.  (See below)

If we look more closely at the numbers, it does say that White will win this game about 73% of the time and it is very close to a double, but not quite enough given the race and the volatility of the position.  It’s hard not to double when you are going to win 73% of the time, and it’s easy to see how, in a couple of rolls, White’s game can get so good that when if finally does double he will get a pass and win only 1 point instead of 2.  But the reason it is still technically wrong to double is that in some cases, getting a drop and getting a sure 1 point beats the “opportunity” to win 2 points, especially when you could also lose 2 points by doubling too soon. 

So technically, according to Snowie, which is generally acknowledged to be better than just about any player in the world, White should not double here. 

But when this position came up in a money game I was playing, I was White, and I have to admit that when I looked at it closely, I wasn’t sure if it was right to double or not.  So I applied a lesson I received from one of the all-time great teachers in the game, Mr. Kit Woolsey, and I applied “Woolsey’s Law.”  And Woolsey’s law states, in part, that if you are not quite sure whether to double or not, you are better off doubling.  Why?  Because if you double, you might be making a mistake, and maybe not.  If it turned out to be the right decision, great.  But if it was the wrong decision, two good things might happen:  fist, you might go on to win the game anyway if your opponent takes the cube, and second, IT IS ONLY IF YOU DOUBLE THAT YOU GIVE YOUR OPPONENT A CHANCE TO MAKE A MISTAKE! 

Maybe he will drop a cube you were not supposed to double.  And maybe he will take a cube you gave him that he should have dropped.  If you are not sure if it’s a double and you don’t double, THERE IS NO CHANGE FOR YOUR OPPONENT TO MAKE A MISTAKE. 

In this particular case, Snowie gives us another little clue about the cube decision.  Next to where it says “Normalized points per game” there is the figure “10%.”  What this is saying is that although it is not right to double here, if 10% of your opponents might drop this cube, that makes it worth the risk to double. 

Again, back to the game I was playing….my opponent dropped.  So, according to Snowie, though I had made a 2.6% error in giving the cube, my opponent made a 24% error by dropping it.  And what really matters to me, and to my pocket book is not that I made a 2.6% error, but that my action caused my opponent to make a much bigger error. 

So the lesson is, when you are not sure about doubling, double.

(Note:  Phil Simborg is a backgammon teaching professional.  He can be reached for comments, questions, advice, and lessons at psimborg@sbcglobal.net.)