Sunday, 6 March 2011
Usually in this blog I try to focus on my own mistakes. It's good for my own learning process and avoids exposing people to unwanted criticism. Occasionally though, I get permission to feature somebody else's errors and here are some from a regular opponent on Fibs. He's ranked at 1755 which will give you some idea of where he stands in the hierarchy.
His problems, like those of so many, revolve around cube use. His checker play is quite good, but he has the worst possible combination of cube errors. He doesn't double early enough, he cashes games that are too good to double and tragically, takes some passes. Our latest match lasted for 13 games, of which he won 7 but lost the match 9-7.
Here's where the points went missing.
Red is on roll, he trails 0-2 to 9 and he leads 108-118 in the race. Should he double? Unquestionably yes. There are two ways of arriving at this. The first will stand repeating yet again, it is Woolsey's Rule. It goes, "Look at the position from your opponent's point of view. if there is any doubt about the take, it must be a double". "Any doubt" is the key phrase here, it means that if you are not 100% certain that it is a take, it must be a double. Actually it is a take, but certainly if doubled here I wouldn't be 100% certain and I certainly didn't want to be cubed.
The second way to look at it is this, an acronym called PRAT. This stands for Position, Race and Threats. Traditionally an advantage in two of these areas is thought to be enough for double and take and an advantage in all three is double and pass. Actually this is a bit too crude and you need to refine this a little and ask yourself how big these advantages really are, but it will do for this position. Red's Position is a bit better as White still has a man behind a four prime, but this is mostly counter-balanced by the fact that White is at least at the edge of the prime and his own strong board will make hitting loose by Red a risky option. The Race favours Red but it isn't overwhelming; a ten pip lead in a 108 pip pure race would be a take. The Threats favour Red, threats being sequences that lose the market, e.g if Red hits and White dances, then White will no longer have a take. We can see here that all the doublets are excellent, as well as 4-3, 4-2 and 3-2, that's 12 numbers straight off. In addition all the above average rolls play safely and there are only a couple of lemons, 2-1 and 3-1. So all in all, strong double for Red, uncomfortable take for White.
This next one isn't quite so obvious, what's the correct cube action here?
Red trails 1-2 to 9, but leads in the race 108 to 132. Woolsey's Rule, are you sure that this is a take for White? If you said, "Yes I'm sure", then you are a bit wide of the mark as this is actually a pass! Positions where you are anchored on the 24 or 23pt and your opponent has escaped all his men and leads in the race are usually passes. Don't be misled by the fact that White holds the 16pt as well. It isn't going to bother Red much on the way home and those checkers aren't much use to White until they move round to complete his board. If you are doubtful about doubling this as Red (or passing as White), set up the position and play it out 50 times. You should find that White will win 23-24% of these, but 11-12 of his losses will be gammons and that's enough to make it a close pass.
Another way of looking at doubling decisions is to adopt the advice contained in Clausewitz's Rules of War; "Always do what your enemy least wants". As Red the last thing that he wants is to be doubled here isn't it? If you evaluate this rather conservatively and think that this might be a double and might not, then Clausewitz has advice for that too. "Faced with two courses of action that are approximately equal in strength, choose that which allows your enemy the opportunity to make a mistake". If you leave the cube in the middle, no chance of a mistake. If you double on the other hand, he may take when he should pass (as here) or pass when he should take. I might well have taken this.
Moreover, once you have doubled you can't then make another doubling error, whereas the enemy may make several. There are many players who hate to double you in with a 4 cube, actually the player playing Red here is one of them. You can double these players in very early indeed, because they don't get the vig associated with owning the cube! All of these guidelines point to being aggressive with the cube.
In my next post we'll look at some more positions from this highly instructive match and discuss the important concept of volatility, but in the meantime, enjoy the game!