the dorbel daily

Tuesday 30 November 2010

The Last Game, Mochy v. Birkhahn







So, runnerup, Martin Birkhahn playing the White checkers has jumped into the lead, 8-7 to 11.

WHITE: (4 2) 8/4 6/4
2. RED: (6 5) 24/13
WHITE: (6 3) 24/18 13/10
3. RED: (4 1) 13/9 8/7*
WHITE: (6 5) bar/20 24/18*
4. RED: (3 1) bar/22 6/5*
WHITE: (3 2) bar/20*


Up to now we've seen a standard blot hitting contest. Now White has a choice of hits and bar/22, 18/16* is best to keep the return shots down and deny Red good fours and sixes from the bar. The match play is an error costing about 0.05ppg.
5. RED: (6 3) bar/22 13/7*
WHITE: (1 1) bar/23 6/5(2)
6. RED: (2 1) 7/5* 6/5
WHITE: (5 3) bar/22 10/5


A poor effort from White. The checker on the 10pt is in no great danger and is badly needed to make the bar. Bar/22, 23/18 is a possibility but bar/22, 13/8 looks best and tops the rollout by a narrow margin. The match play is an error costing 0.098 ppg.

7. RED: (4 3) 13/9 13/10
WHITE: (6 5) 13/2
8. RED: (6 4) 8/2* 6/2


A blunder. Making the 2pt on White's head puts a man on the roof against a three point board but the price for doing this is much too high. It gives up the 8pt, an important element of his prime field and buries two checkers deep in the home board. Now he is comitted to blitzing at a time when he has three men back behind a useful broken four prime. A much better play is 24/14 and the match play costs 0.144ppg.


WHITE: (6 3) bar/22 8/2
9. RED: (3 1) 10/7 8/7
WHITE: (6 3) 13/4


Martin makes a nice looking play that keeps all his checkers in front of the anchor, at the cost of leaving a direct shot. However, the pragmatic and ugly 13/10, 8/2 is better. There are two reasons for this. Firstly White leads by 31 pips after the roll, so he doesn't need to risk losing part of that in an effort to make the 8pt. You don't need to block checkers that have no intention of leaving. Secondly, Red has got himself into another TMP position, so he has to break a point next turn if he can't play all the roll with his one spare or roll a useful doublet. He will welcome the chance to solve this problem by putting White on the roof. However, White's play is nice and pure and the position after 13/10, 8/2 is so ugly that that the match play error only costs about 0.050ppg.


10. RED: (5 3) 22/17*/14
WHITE: (4 2) bar/21 13/11*
11. RED: (6 2) Can't move


This position, with White on roll and Red on the bar neatly demonstrates the importance of adjusting your cube action to the score, particularly near the end of a match. If the scores were reversed (to Red 8 White 7), then White would have a double here and Red would have an enormous pass. As it is White that leads, doubling would be a serious error and he has to play on and try for an undoubled gammon. The strength of his position is the big double threat, as 41 of his 64% wins here (Snowie evaluation) are gammons. If White turns the cube, half of the extra points that he gets for his gammons are wasted in overage and if Red redoubles, White's gammons are useless! White correctly waits.
WHITE: (2 2) 11/7 5/3*/1*
He could also have played 13/9, 5/3*/1* . The two plays come out nearly equal in a rollout.
12. RED: (3 1) bar/22 bar/24*
WHITE: (6 2) Can't move
13. RED: Double


Mochy (Red) doubles from the bar. This to me is a brilliant double, recognising that he is now the favourite (about 60%), he wins a lot of gammons (27%) and that White's three blots mean huge volatility. This cube is based entirely on the score. After White correctly takes (passing would be a very large blunder) Red's 4 points for a gammon get him neatly to the winning post. White can only use three of the points for his gammons and the cube isn't much use to him either. Redoubling opportunities will be very limited.
With careful and quiet analysis all this seems very obvious, but kudos to Mochy for spotting this opportunity over the board and wasting no time in shipping it in. That's why he's Number One in the world right now.
WHITE: Take
14. RED: (6 1) bar/18*
WHITE: (5 3) bar/22
15. RED: (6 1) 13/12*/6


A tough play for Mochy with many feasible choices. His play looks natural, but the rollout shows that it is best to hit with the 1 and play 24/18 with the 6. This is a problem that crops up constantly in situations like this. You can either focus on making points in the home board (and/or hitting) or you can use the roll to improve on the other side of the board. 24/18 locks up the escape and takes total control of the outfield and on this occasion that is a little more important than providing an extra builder for the 4pt. I often get caught out with this one too. The key questions are, "How difficult is the escape?" and "How important is it to make the home board point?"
The match play is a medium error costing about 0.06ppg.


WHITE: (3 2) bar/22
16. RED: (1 1) 9/8(2) 6/4*
WHITE: (3 2) bar/22
17. RED: (6 3) 13/4
WHITE: (2 1) bar/22
18. RED: (6 2) 24/16
WHITE: (2 1) 4/1


White eschews the hit but it is probably worth doing. A constant theme of priming battles is not giving your opponent complete freedom to play anything. If Red re-enters on the 22pt, White is no worse off. If Red re-enters on the 24pt and hits, White is hardly much worse off than he is now and at least Red will be back behind a broken four prime. The match play is a very small error at worst.


19. RED: (4 4) 18/14 16/4
Mochy elects to stay back and try for another checker, but the simpler 22/6 is probably a little better. A very small error at worst
WHITE: (4 3) 5/1 5/2
20. RED: (3 1) 4/1 2/1
WHITE: (3 2) 6/3* 6/4
21. RED: (5 3) bar/22* 7/2
WHITE: (6 4) Can't move
22. RED: (3 1) 22/19 7/6
WHITE: (6 3) bar/16
23. RED: (3 1) 14/10
WHITE: (6 3) 22/16 4/1
24. RED: (3 1) 10/6
WHITE: (6 5) 16/5
25. RED: (4 2) 19/15 6/4
WHITE: (3 2) 16/11
26. RED: (2 1) 15/14*/12


Mochy hits of course, but the best 2 may be 8/6. It's usually right to start clearing an awkward point while the defender is on the roof, particularly as here when White has a busted board anyway.


WHITE: (1 1) Can't move
27. RED: (5 2) 12/5
WHITE: (6 2) Can't move
28. RED: (5 5) 6/1(3)
WHITE: (5 2) Can't move
29. RED: (5 2) 8/1
WHITE: (4 2) Can't move
30. RED: (6 4) 8/4 5/off
WHITE: (4 3) bar/18
31. RED: (6 2) 5/off 4/2
WHITE: (3 1) 22/18
32. RED: (3 2) 5/2 4/2
WHITE: (3 1) 22/19 18/17
33. RED: (3 2) 4/1 4/2
WHITE: (5 3) 19/16 17/12
34. RED: (6 4) 2/off(2)
WHITE: (6 2) 22/20 12/6
35. RED: (4 3) 2/off(2)
WHITE: (6 4) 16/6
36. RED: (6 5) 2/off(2)
WHITE: (6 2) 20/12
37. RED: (6 3) 1/off(2)
WHITE: (5 3) 18/10
38. RED: (6 1) 1/off(2)
WHITE: (5 4) 22/17 22/18
39. RED: (4 1) 1/off(2)
WHITE: (3 1) 10/6
40. RED: (3 2) 1/off

.........and Mochy wins a gammon and the match.

I do hope that this has been an instructive exercise for you. Working through every move has taught me a lot for sure. Close examination of the moves and cubes of players of this calibre always pays dividends. Congratulations to both players and big thanks to Mochy for doing us the honour of visiting our site to play our champion.

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