Okay, my checker play skills continue to improve, while my cube skills stay on a horrible PR 20 “casual player” level. Time to practice. Maybe you’d like to join – I’m taking cubing positions from the wonderful bgtrain.com that I failed to assess correctly and discuss them here. Did you find the right answers?

Enjoy!

Position 1: Doubling against a back game

I was guessing this is a “no double / take”. In my experience, a 43 backgame is a strong backgame; white has some timing to fix his board until black might run into trouble. I considered the fifth man behind an asset rather than a liability – gives white plenty of timing.

But the machine thinks otherwise:

Seems I was both right and wrong – black’s winning chances are not high enough for a double – white will win over one in three games. However, I didn’t take the gammons into account. And with five checkers back white, if black manages not to get hit, or even occupy the 2 point and let white dance for a while, there will be gammons. 28% gammons is a lot, turning the decision into a double/pass.

Position 2: Late-Game Hit: Redouble or not?

This is obviously a game that went well for white, who doubled and then got hit immediately before bearoff. However, black has not built a strong board yet. Should black redouble?

My reasoning was that black’s board is not strong enough for a redouble. (S)he has good chances to make the 5 point, but if (s)he fails or white enters with something like 64 or 54 this can easily turn around. Black has some outfield control but not much.

But again I was wrong. Not re-doubling is a serious blunder.

I must confess I’m a bit confused by this analysis – 70% isn’t too much, 4% gammon chance also not overwhelming. It’s also not the close match – if black redoubles in a match to 5 pt, white doesn’t gain much by owning the cube. But also in a money game, black should double (although it’s not a -0.15 blunder but only a small -0.05 mistake to not double).

Hm, maybe I was just wrong about the 75% you need to redouble? Anyway, the biggest portion of my blunder was not seeing that white re-cubing this re-cube has little value, and that in a match to 5, recubing to 4 is doesn’t require as big of a lead as a money game recube.

Take against a weak board and many opportunities?

In case you’re wondering – this is a screenshot using BGBlitz and one of its beautiful designs.

This is a tricky one. Black has a very strong board, white a blot and a weak 3-point board, but black has one checker on the bar, white has >50% chance of hitting a second checker. But white also has to take care of its own blot urgently – if it can’t cover and black comes in with a 5, the game will turn around.

I decided all these factors are well enough to take.

Wrong. Again. And badly wrong at that.

Taking is a -0.457 super blunder. kruidenbuiltje has given a great explanation on the page: “Red has good diversification: 1,3,6 + {D4,D2,42} = 31/36 covers. Of those {24,D2,D4,23,21,43,41,62,64,D1} = 17/36 hit + cover. And then there is the match score, and the double kills the cube for white. At 0-0(5) it is a Take.”

And he’s right :-). As a money game this is a take, as a redouble to 4 of a 5pt game it is a pass.

It’s the match, stupid

This is all about the match score. White has 83 pips to go and only a lead of 5 pips. An easy take. If this wasn’t a match to five where white trails 1-2. If blue takes, the game is about the match win. If he drops, he trails 2:3. So while white has only 70% wins and 0% gammons, blues prospects of winning the match are better at 2:3 (where, if we trust XG2, he still will win 40% of the matches, not just 30%).

Do I need to stress that I, roughly remembering a rule about racing lead and taking once the groups have split, decided to take?