the dorbel daily

Tuesday, 10 January 2012

The Answers Part Two

The answers for Numbers 6 to 10

Position 6

Money game, Black to play 3-3.
The plays that include 5/2*(2) do very badly in the rollout. Switching from priming to blitzing when you have already cubed and you don't have the ammo in position for the attack just isn't the plan. That solid 7 to 4 block is Black's big asset and shouldn't be traded away. Rather surprisingly Bill Davis and Danny Kleinman liked bar/22, 13/10, 5/2*(2) back in 1990 and so did Barclay Cooke when he showed the position as No 102 in Paradoxes and Probabilities. That's a shockingly bad play and so is hitting twice! So, what's best? It's probably one of these, either bar/22, 21/18*/15, 13/10 or bar/22, 24/18*, 13/10. The rollout hasn't split them yet. If it does I'll let you know and for now I'll allow either as the winner. Two entrants got the first of these.

Position 7.

Money game, Black to play 5-1.
All good quizes need a position like this. The answer is of course 7/2, 7/6, for minimum shots and to avoid the 6-6 disaster next when not hit.
Two entrants got this right.

Position 8.

Make the play of 6-6 that leaves the fewest shots.
Dead sneaky this one. The answer is 14/2, 10/4(2). This appears to leave 11 shots, but actually only leaves 5. You have to play the full roll if you can, so White can't hit with 6-1, 4-1 or 2-1!
Only one entrant got this right and he was honest enough to say that he had seen it before and remembered the trick.

Position 9

Money game, Black to play 1-1.

2/off(2), More wins, more gammons, more backgammons. It does leave a big mess after rolling a 1 next turn, but for that to hurt you have to roll a 1, get hit, hit back and then get hit. That's 30% x 30% x 30% x 55% = somewhere between 1 and 2% and even then you haven't lost as you own the cube. Gumpi also cleverly points out that playing 2/1(4) creates 2-1 as a blot number next turn. Only one entrant got this one right.

Position 10

Money game, Black to play 5-3.
24/21, 9/4. When you have to leave a blot, or as here blots, put them where they will do most good if not hit. This play at least puts the blots on points that Black really wants. 11/8, 9/4 is the only alternate that comes close on XG++ but I admit that I haven't rolled this one out yet. Our experts from 1990 also picked this play and 3 of the class of 2012 also nailed it.

So after all that, who won? Stiefnu scored a brilliant 7/10 just squeezing in ahead of Timothy Chow who totalled an excellent 6. Well done all of you and thank you very much for taking part. This blog is nothing without you. If Steve sends me his address I'll send him his wonderful prize, which I just know he will treasure.

Until the next time, enjoy the game!


Timothy Chow said...

Thanks, Paul, for running this quiz. I enjoyed it. Good to see that Position 7 was an anti-QF question. Next time I'll try to avoid second-guessing!

In position 6, I'm wondering if switching points with 5/2*(2) is best at gammon go. GNU 2-ply seems to think so, by a narrow margin.

What was the prize, by the way?

dorbel said...

Thanks for playing Timothy. XG clearly likes the double hit at GammonGo, not unreasonably.
Steven hasn't yet received his prize, but I'll tell you what it is when he has!

dorbel said...

Interestingly, the original answer of bar/22, 13/10, 5/2*(2) emerges from the mists as a viable contender at GammonGo. It does diversify nicely, with fives, fours and twos and 1-1 to make or attack the 5pt, sixes and threes to pick up the third checker.