the dorbel daily

Sunday 31 October 2010

Mochy v. Birkhahn, Game Three

Game Three, Red leads 4-1........

WHITE: (4 1) 24/23 13/9
Martin might also have tried 13/9, 6/5, almost as good in theory and more gammonish
2. RED: (5 4) 24/20 6/1*
24/20, 13/8 and 24/15 are more usually tried here, but Mochy has picked this play up from the bots. Its sole purpose is to take away half of White's next roll and it usually leads to a difficult passage of play, ideal for a strong player.
WHITE: (4 2) bar/23 13/9



A tough play straight away for White. The match play looks reasonable; an anchor, an outfield point and no blots, but this is probably third best. Bar/23, 9/5* is better, winning (and losing) more gammons than the other plays, but the best is bar/21, 23/21. Taking a high anchor may appear defensive, but it does allow White to attack with freedom if he gets the chance. Red doesn't gain much by hitting on the 16pt and in fact will sometimes eschew it in favour of anchoring. A very difficult roll to sort out over the board, hard to blame Martin for this medium sized error.
3. RED: (6 1) 13/7 8/7
WHITE: (1 1) 23/22(2) 6/5*(2)
This looks like the best play, but 23/21, 6/5(2) is also strong, taking the opportunity to diversify while Red is in the air and has a blot inboard. 8/7(2), 6/5*(2) is also appealing at first view, but it doesn't play so well and is clear third in the rollouts. It's not that it's a bad plan, just that developing the two men at the back is better. After this great roll White is close to the doubling window next turn, so he doesn't need to make big plays. He can just tiptoe towards an optimal cube, hence his good play here.
4. RED: (4 3) bar/21 24/21
WHITE: (6 1) 13/7 8/7
5. RED: (5 5) 13/8(4)


Mochy made this play fairly quickly, indicating confidence and Gnu 2-ply will play this, but Snowie marks it as a blunder and prefers to bury some checkers behind the anchor. A long rollout doesn't really seperate the best plays convincingly, so note that 13/8, 7/2(2), 6/1 is probably equal to the match play and 13/8(2), 7/2(2) might be slightly inferior. I like the match play for what that's worth.
WHITE: (1 1) 13/12(2) 12/10
This position and this play deserve a post all of their own, which precedes the analysis of this game.
6. RED: (5 1) 8/7 6/1
WHITE: Double


This is technically too early. It isn't very gammonish and the whole position is rather static, so very few ways to lose the market. Even if White makes his prime, he doesn't always lose his market and often has an optimal double. Only a very small mistake though.
6. RED: Take
WHITE: (6 2) 22/16 12/10
8. RED: (5 2) 8/6 7/2
There we saw a sequence where White rolled his best number and Red rolled poorly. If the cube were still centred, this would be a strong double for White and a correct take for Red!
WHITE: (3 2) 22/20 16/13
Probably a small error. Red still leads in the race and White needs to catch up, as well as angling to pick up another checker back if he can, so plays like 16/11 or 16/14, 6/3 make sense. Either of these may generate a shot or force Red to bury more checkers. The risk of being trapped is very small, so well worthwhile.
9. RED: (4 1) 8/7 6/2


Mochy might also have tried 7/3, 7/6 to clear a point.
WHITE: (6 4) 20/14 13/9
Nothing to be gained by staying now and a few bad sequences if he does, so White correctly leaves.
10. RED: (4 1) 7/3 6/5
Mochy slots two points to complete his board as fast as possible.
WHITE: (4 4) 14/2 9/5
11. RED: (4 2) 8/4 7/5
WHITE: (3 1) 6/2
12. RED: (5 1) 8/3 5/4
WHITE: (6 2) 7/1 7/5


This is just wrong. "Break from the back and don't ask questions" is usually right and it's right here. While Red has a good home board, White needs to concentrate on the bear-in. The match play is an error costing about 0.05 of a point.
13. RED: (3 2) 8/5 7/5
WHITE: (6 2) 8/2 8/6
14. RED: (6 1) 5/4
WHITE: (4 1) 5/1 2/1
This is the wrong idea too. Red still has a closed board, so safety remains the priority for White. 10/6, 10/9 is correct and the match play is a small mistake.
15. RED: (5 3) 6/1 6/3
WHITE: (3 3) 10/7(2) 9/6(2)


Now Red's board has cracked and he has to leave next turn with sixes and fives. White no longer has to make safety his main priority and will want to attack any checker that gets left behind, in order to activate a small gammon chance. 9/3(2) is the best play. After that, only 6-6, 4-4 and 3-3 escape without leaving a shot. After 10/7(2), 9/6(2) red can get away with 6-6, 5-5, 4-4, 6-5, 6-4 and 5-4. Moreover White's attack will be less effective with a four point board than a five pointer. The match play is a small error.
16. RED: (3 1) 4/1 3/2
WHITE: (5 3) 6/1 6/3
17. RED: (6 5) 21/15 21/16


Yet another apparently routine but actually difficult play, this time for Mochy. 21/10 is the best play, staying back for shots after 6-6, 6-3 and 4-3, as well as forcing White to waste pips with 5-3. Hard to evaluate over the board but 21/10 is clearly right and the match play is an error costing 0.06.
WHITE: (4 2) 7/3 6/4
18. RED: (3 1) 16/12
WHITE: (2 1) 7/5 1/off
19. RED: (5 1) 12/6
WHITE: (5 3) 5/off 3/off
20. RED: (6 6) 15/3 6/off 5/off
WHITE: (3 3) 6/off(2)
21. RED: (3 3) 5/2 3/off(3)
WHITE: (6 5) 5/off(2)
22. RED: (6 5) 4/off(2)
WHITE: (5 3) 5/off 3/off
23. RED: (6 2) 2/off(2)
WHITE: (3 2) 4/1 2/off
24. RED: Double


Clear double for Red of course and usually a pass, but not here. White can take with 20% at this score and he has that. Martin doesn't give up much by passing though, a medium error costing 0.056.
WHITE: Pass


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