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.

Wednesday, 27 October 2010

Mochy v. Birkhahn, Game Two (Part 2)

So, taking up where we left off, Red has just redoubled to 4 and White took, leaving the position above.

14. RED: (4 2) 23/21 13/9
Note here how Mochy uses this roll to do two good thing, make a good anchor and diversify his spares on the midpoint. The anchor is insurance against a bad sequence and 13/9 provides another builder for the vital 4pt. Continuing the blitz on this roll with 5/1* would be a big mistake. That builder is needed for the 4pt and the match play allows Red to select one of several game plans as the dice decide.
WHITE: (6 2) bar/23 11/5

This is a sizeable error by Martin. 21/15 is better, taking his chance in the outfield rather than being attacked on the 21pt. If Mochy hits in the outfield, he can't also make the 4pt, except of course with 3-3 which is a huge roll anyway. This is not an isolated case. In general you don't want to be on the point that your oponent wants next when he has builders lined up ready to pounce.
15. RED: (6 3) 13/4*
Another strong play from Mochy. The 4pt has MIP (most important point) status for both sides. If Red can make it he will effectively strangle White, if White can make it he will have good chances in a mutual holding game, particularly as he now holds the cube. 13/7, 9/6 is much too timid.
WHITE: (6 4) bar/21* 23/17

Brilliant. How many of us would have found this play instead of the "obvious" bar/21*/15? Why is it best, when it was correct to step out in the previous diagram? There the danger lay in Red hitting on and simultaneously making the 4pt. Here he can't do that, so White can leave it slotted as a point that he very much wants to make. Very easy to see now, but it also requires considerable courage to lay out 4 blots with the cube on 4! Note that fives and ones are duplicated and that the match play exerts a huge threat on Red's outfield blot. Well played.
16. RED: (6 3) Can't move
WHITE: (3 3) 24/21 17/14 13/10(2)
17. RED: (3 3) Can't move
WHITE: (6 2) 23/21 14/8

I don't see the point of this play. White doesn't have a cover number for the 8pt unless he gives up the more useful 10pt, so the blot is just a blot on the landscape. Moreover it creates a large gap between the 21pt and the 10pt. Keeping your checkers connected, i.e. within six pips of each other, was a feature that the old masters stressed constantly. It's less fashionable now in these more dynamic days, but still important here as White seeks to bring his back checkers out and round. 23/21/15 is the best play and the match play is an error.

18. RED: (4 4) bar/21 21/17*(2) 13/9
This is probably best, but bar/21, 21/17*(3) is almost equally good in the rollout. Making the 9pt is less valuable than usual as Red is now the pip leader again and doesn't need a blocking point that he will have to clear later. However it is a useful landing point. bbbbb
WHITE: (5 2) bar/23 7/2
19. RED: (6 3) 21/18*/12
WHITE: (6 1) bar/24 21/15
20. RED: (2 2) 12/10*/8 5/1*

I don't understand this play. If you are going to hit loose on the ace point you may as well make it. 12/10*/8, 3/1*(2) seems clear to me. The second best play in the rollout is 13/11, 12/10*/6 which demonstrates how damaging it is to be hit immediately. 13/11, 12/10*, 3/1*(2) doesn't do as well as any of these, presumably because getting a checker onto the 8pt is very important. Ibbbbbbbt has two functions there, being both a slot for the 8pt and an extra builder for the 2pt as required.
WHITE: (4 2) bar/21 bar/23
21. RED: (6 3) 17/8
WHITE: (3 2) 10/8* 5/2
22. RED: (6 2) Can't move
WHITE: (6 5) 21/15 10/5

When I first looked at this position I liked 21/10. Making the point 6 pips away from the "escape hatch"(here the 21pt) is usually very strong, guaranteeing that the checker on the bar can't enter and escape without leaving a shot. However the match play does best in the rollout, partly because it increases White's chances of picking up a second checker and partly perhaps, because it is slightly better connected. White might well want to make the 15pt for outfield control and as a staging post for the back men when they leave.
23. RED: (5 4) bar/16
Looks like a small error for mochy here. Bar/21, 13/8 leaves fewer shots and gets down to one blot.
WHITE: (2 1) 15/12*
24. RED: (4 2) bar/21 16/14
WHITE: (2 1) 12/11*/9
25. RED: (6 4) bar/15
WHITE: (6 5) 21/15 9/4*

Nobody liked this play at first sight and indeed snowie 3-ply marked it as a blunder. However a rollout shows that it is only a small mistake at worst. Hitting loose leaves 15 shots, whereas 21/10* only leaves 11, but note the better diversification after 21/15, 9/4*. If Red dances, White has sixes to escape, fives to hit a second checker, fours and ones to make a five point board and twos to get to the edge of Red's prime. After 21/10*, White has duplicated his own sixes and will often have to hit loose next turn anyway. So, interesting play, even if probably a small mistake.
Facile to point out how much White regrets not having played 23/21 with his two last turn.

26. RED: (5 2) Can't move
WHITE: (3 3) 15/6 4/1
White rolls a lemon; only 5-5 is worse. His play is good, probably equal to 15/6, 8/5 which concentrates on making the 4pt at the expense of duplicating his own twos

27. RED: (3 2) Can't move
WHITE: (6 2) 23/15
28. RED: (1 1) bar/24* 15/14 5/4*(2)

It's a great roll but how to play it? It's obvious that Red is going to put two men on the roof, but which two? Mochy though it right to play 5/4*(2) but giving up his 5pt is very damaging. A good sequence for White with the 20pt open might be a winner and it is pretty clear that Red needs to keep his five prime. Gnu 2-ply will play the same move as Mochy, but rollouts on Snowie and Gnu agree that this is a blunder. Bar/24*, 3/2*/1, 3/2 tops the rollout, with bar/24*, 15/14, 3/2*/1 a close second. Bar/24*, 15/14, 3/2*(2) is third and is a small error. This must be that if it comes to a blitz, as it often does, the 2pt or the 3pt are easier to cover than the 1pt. Note that plays including 15/14 expose Red to the superjoker 4-4 from the bar.
WHITE: (2 1) bar/23 bar/24*
29. RED: (5 1) bar/24 14/9
WHITE: (2 1) 6/4 5/4
30. RED: (6 4) 24/14
WHITE: (5 3) 23/15
31. RED: (6 5) 24/18 14/9
WHITE: (3 3) 23/20 15/12(2) 8/5
32. RED: (6 5) 18/7
WHITE: (3 1) 24/20
33. RED: (3 1) 9/6 9/8
WHITE: (2 2) 12/8 5/1
I can't see the point of slotting the ace point; 12/6, 12/10 looks better, but it doesn't matter much.
34. RED: (4 3) 8/1
WHITE: (6 3) 12/3
35. RED: (5 2) 7/2 3/1
WHITE: (2 1) 8/7 3/1
36. RED: (4 2) 8/4 8/6
WHITE: (5 2) 20/13

Martin correctly runs while Red has two blots inboard. He still trails by 7 after the roll, but he isn't going to get a shot next turn so trashing the board and hoping to win after a shot in two or three turns time isn't realistic. Staying back also wastes pips in a close race. Good play.
37. RED: (5 4) 7/2 7/3
WHITE: (3 3) 20/11 13/10
38. RED: (6 6) 9/3(2) 6/off(2)
WHITE: (2 2) 11/9 10/6 7/5
39. RED: (2 1) 2/off 1/off
WHITE: (4 2) 9/5 2/off
40. RED: (6 4) 6/off 4/off
WHITE: (6 1) 6/off 1/off
41. RED: (6 5) 6/off 4/off
WHITE: (3 1) 3/off 1/off
42. RED: (3 2) 3/off 2/off
WHITE: (6 3) 6/off 3/off
43. RED: (6 1) 4/off 1/off
WHITE: (5 3) 6/3 5/off
44. RED: (3 2) 3/off 3/1
WHITE: (3 2) 3/off 2/off
45. RED: (4 1) 3/off 1/off

And Mochy wins 4 points to lead 4-1 going into the third game. We'll add that one next week.
Looking at some of these positions and waiting for rollouts can be time consuming so be patient. I do hope that you are enjoying it and learning from it. You'll get the most benefit if you play the rolls out on a board, rather than just looking at the diagrams. Until next week, enjoy the game!

Tuesday, 26 October 2010

Mochy v. Birkhahn, Game Two (Part 1)

So, Martin Birkhahn (White) leads 1-0, let's take a look at the first part of game two, a thriller full of tough plays, big swings and cube action.

WHITE: (6 1) 13/7 8/7

2. RED: (1 1) 8/7(2) 6/5(2)

WHITE: (2 1) 13/11 6/5

Martin makes a big blunder with this roll. He is already in some danger of being primed on the other side of the board, so he makes a play that aims to diversify and build a prime of his own. Actually if he wants to do this, 7/5, 6/5 is better. Owning the 5pt with the bar slotted has to be better than owning the bar with the 5pt slotted. However, the whole plan has a basic flaw, which is that even if he isn't hit, he will always be playing catch up. Red either hits or brings down builders for his own prime without much danger. What White needs to do here is to take advantage of Red's temporary shortage of builders and split at the back. 24/21 or 24/23, 13/11 are both much better than the match play but best of all is 24/22, 24/23. This puts the most pressure on Red's slot and has the best coverage of the outfield. This is similar to a position that I posted on Sep. 15th, take a look back.

3. RED: (6 3) 24/15

This is a reasonable play from Mochy. The bots have trained us to run out in this sort of situation and take our chances there, rather than be attacked inboard, but 24/21, 13/7 may be better. The 21pt blot isn't in much danger and 13/7 adds a very useful checker to the attack zone. Snowie plays that and the rollout suggests that it is marginally better.

WHITE: (4 2) 11/5

4. RED: (6 4) 15/9 13/9

WHITE: (6 1) 24/17*

5. RED: (4 2) bar/21 24/22

WHITE: (5 3) 8/3* 6/3

6. RED: (5 3) Can't move

WHITE: Double

White on roll, Red on the bar, race lead, threats and a better position, so a mandatory double and another tough cube decision for Mochy. However, although he is on the bar, he has a few things going for him here that he didn't have in the first game. He has a broken 4 -prime of his own, he only has two blots and very importantly, White hasn't made his 4pt yet. Owning 6-5-4pts is much stronger than 6-5-3 and I think this may have been the key factor that got Mochy to take. Snowie makes this a close pass, so not a very bad decision, particularly as it is a high skill position with a long way to go. A technical error, but in match play a marginal take/pass.

6. RED: Take

WHITE: (5 4) 13/4*

8. RED: (5 4) bar/21*

WHITE: (6 3) bar/22 17/11

9. RED: (2 1) bar/23 6/5

I like Mochy's play here, but bar/24, 13/11 is probably equally good. It diversifies nicely in Red's outfield and the extra blot doesn't make the position much more gammonish according to a rollout.

WHITE: (6 2) 8/2* 6/4*

Excellent play. Most players are reluctant to leave 2 blots inboard, but Martin is an expert and makes the play most likely to win and the most likely to win a gammon. It leaves 21 shots from the bar but 11/5, 6-4* leaves 20 and only puts one man up, no contest.

10. RED: (6 4) bar/21*

WHITE: (5 5) Can't move

11. RED: (6 1) bar/24, 9/3*

WHITE: (6 2) bar/23

Red has a very strong double here, in fact he may well have been in the window on his previous roll! Mochy certainly thought about it. With 4 blots on the board and a fifth on the bar, this position is about as volatile as is possible. Moreover every single Red roll plays well. The worst is probably 5-3 and even that makes a third point inboard and puts a second man on the bar! I mark this as a marginal take/pass for White, but over the board I would have happily scooped. Food for thought for all of us and a very instructive position to practise with. Red rolled...

12. RED: (6 1) 24/23* 9/3

WHITE: (4 3) bar/21

13. RED: Double


Clearly Red has improved a lot and doubles. As White had a marginal take last time he should pass this, but Mochy's "wait and see" tactic pays off big time and he gets a take! Large blunder from Martin. Five blots including the man on the roof makes this far too gammonish for a take.

So, what happened next? Join us later in the week for the rest of this great game.

Monday, 25 October 2010

Mochy v Birkhahn

Last Saturday we were treated to an exhibition match on Fibs. Runnerup (Martin Birkhahn) was the Fibsleague Master's Champion for 2009 and Franck del Rio, the Director of Fibsleague arranged for him to play an exhibition against Masayuki Mochizuki from Japan. The current world champion Mochy, as he is known for obvious reasons, is a great ambassador for the game, travelling the world to play backgammon and impressing everywhere with his skill.
The 11 point match was watched by an enthusiastic crowd of 30 -40 fibsters and over the next few days I want to take a look at some of the more interesting plays.
Set up a board and follow the play.
Mochy is playing the Red checkers and Martin the White. Here's how game 1 went.

1. RED: (6 3) 24/18 13/10

WHITE: (3 3) 13/7*(2)

This is the best play, hitting, making a good point and moving two more checkers into the attack zone all in complete safety. You often see 13/7*, 8/5(2) 0r 13/7*, 6/3(2), but they make more sense when trailing in the match and you need to go after a gammon from the word go.

2. RED: (4 2) bar/21 10/8

Mochy commented, "Already I don't know what to do". It's the third move of the game and a master is puzzled, which shows you how hard backgammon can be. He opted for the simple play, no doubt feeling that four blots was a bit much even for the opening. It's a close call. Bar/21, 13/11 is probably equally good, with lot's of potential for development if he isn't on the bar next turn.

WHITE: (6 4) 13/7 8/4*

White has the checkers for a blitz and opts for the natural-looking 13/7, 8/4*, but this looks like a small error. He leads by 14 pips after the roll, so he doesn't need to try for the blitz and leave 20 return shots. The computer play is 24/20, 13/7. I can't say that I would have found this over the board, but Snowie likes it best.

3. RED: (6 6) Can't move

Whoops, 6-6 from the bar. With his lead and his attacking possibilities White is already in the doubling window and could ship one in here. No chance of a bad pass I think, so you can't blame him for waiting, with the match only just under way and a large audience.

WHITE: (4 2) 24/20 6/4

4. RED: (5 3) bar/20 8/5*

Mochy enters with a lemon and does the best he can, slotting both 5pts and putting White on the bar. This is actually a defensive play, taking away half of White's next roll and and giving him a few bad numbers. It leaves this position.....................

..........and it's clear that Martin should double from the bar. Race lead, much better position, substantial threats, it cries out for a cube. Only Martin can tell us why he didn't turn it and we can bet that Mochy was pleased not to be doubled.

WHITE: (6 4) bar/15

White throws one of his bad sixes, so feels pleased that he didn't turn it.

5. RED: (1 1) 8/7(2) 6/5(2)

I'm not sure that Mochy makes the best play here. The blot is useful but subject to 6 hitting numbers, all of which don't play well on the other side of the board. Snowie plays 8/7(3), 6/5, hard to find, but with White about to attack on the other side a bit of solidity can't hurt.

WHITE: (3 2) 8/5* 7/5

6. RED: (4 3) bar/22 5/1*

Again Red makes a defensive hit, hoping to keep White off balance for a roll.

WHITE: Double

Now White doubles from the bar. Mochy thought about taking this one and at the time I thought that it might be a close take, but he summed it up perfectly. "4 blots, outboarded, no anchor, behind in the race, I pass".

6. RED: Pass

So, a short but instructive game. Mochy ends it with a pro pass, but Martin missed two chance to double him in, one slim, one fat. He is usually a pretty aggressive cube handler, so perhaps he is just slow out of the blocks. The lesson to be learned here is that you have to be alert and ready to use that cube, right from the word go. Doubling opportunities can occur from your second roll of the game and you mustn't let them go by.

We'll take a look at the second game in the next post. It was long and complex, so be patient. It might take a day or three to do. Until then, enjoy the game!

Sunday, 10 October 2010

Bots and Backgames

A correspondent offers as an opinion that the positions I showed in the last post should not even be doubles. The reason that he offers for this is, "That bots do not understand backgames". This is an opinion that is held by my many people, some of whom should be listened to because they are respected thinkers, some of whom are merely parrotting what others have said.
Let's sort out some nomenclature. White in the last post is "playing a backgame", i.e. holding two points in the opponent's home board with the hope of generating shots later, hitting one or more checkers and winning the game in that way. Red is "defending against a backgame", i.e. trying to bear in and bear off without leaving any shots, or surviving them or indeed winning after being hit.
Do the "Bots can't play Backgames" set think that the bots play them poorly, or defend against them poorly, or both? I'm not clear on that. Do they think that they play the checkers badly or do they think that they are very badly wrong in their assessment of the possible outcomes of the game to decide upon cube action? Somebody enlighten me here and I will be very pleased to hear opinions, ideally backed up with some data.
Some people I know produce positions, usually composed, that the bot will handle in a very odd way, I accept that, but I don't think that that is evidence that the majority of games are played badly. I also know positions where the bot can be well off the money in non backgame positions.
I will be very happy to play the first position from the last post as a prop, either double against no double or I will pay White a point to take the cube. Props can be set up and played on Gamesgrid. Any takers?
Alternately I will be very happy to take snowie playing either side against a human, each player to take the same side for, say, 50 games. Any takers? A sporting 5 euros a point shouldn't kill anybody and might settle the discussion in this case at least.

Saturday, 9 October 2010

Not What, But Why

Like many other keen players, I run all my matches through a bot for analysis while the match is fresh in my mind. I don't look at every play, or even every error, but the blunders (mistakes that cost more than 0.11) do get looked at. Once I've checked them and satisfied myself that the bot is likely to be correct, it is vital to try and understand the position and how I could have avoided the mistake. Take a look at this next one and you'll see what I mean.

Here I am playing the Red checkers and leading 5-4 in a match to 9. It's a fibsleague match. I think about doubling, but don't. In fact this is already a pass according to Snowie and Gnu and failing to turn the cube is a major blunder. How did this come about? It isn't at all clear that White should take, so by Woolsey's Rule alone I should obviously double. Moreover, there is a very handy rule of thumb for deciding when to double backgames. When you are threatening to clear the third last point in front of a well timed backgame, you are probably in the doubling window. With hindsight I know why I didn't cube here and it's an old failing; I tighten up with the cube when leading in matches that I am very keen to win, particularly when I am playing somebody that I think is not playing well. I drift along, hoping that the match will somehow win itself and tend to be pessimistic in exactly this sort of position. What I should do here is ship the cube in and put the pressure on White, because clearly in this position she would prefer not to have to make a cube decision. It's more or less what I call a 60/40 position, 60 wins including 40 gammons.
Some key points to note: I have lots of spares at the moment, so I can handle all the non-clearing rolls, except 6-1 of course. These spares are very important and when I begin to burn these, my position will get weaker. On White's side she has the nice 6-5-4 block in place, but her other checkers are awkwardly placed, although of course her frontal position should improve. it's important to recognise this "I'll get weaker, while she'll get stronger" scenario, because it happens a lot.
I rolled 6-2 and White rolled 4-1, so we came to this position next.

I have got slightly weaker because I have lost a couple of pips of timing and White has improved a bit because her distribution is better and she has slotted an important point. Now Snowie thinks that this is still a very strong double and White has a tough take. Gnu agrees. Again I didn't double. At least here I was consistent, as I did recognise that I had got a bit weaker, but again the blunder happens because I am reluctant to escalate the cube, a weak-kneed attitude. Backgammon is a game of aggression, be aggressive.
Next I rolled 5-1 and burned my last two spares from the 6pt, followed by White rolling 6-1 and playing 12/11, 9/3. This is a mistake for White. Slotting the next point in the prime is usually right, but here it's one slot too many. White already has the vital bar slotted and it is more important than the 3pt here. In addition, five blots is a lot of weight for any position to carry! The best play looks like the quieter 12/6, 10/9. This is much more balanced and the 9pt is a point in the prime field, six pips away from the 3pt escape hatch. The real weakness of the 3pt slot shows its head on my next roll, 6-2.


With all those blots strung out I should play 8-6 and take my chances now, as White will never be so weak again. Sadly this world class play passed me by and I played the feeble 5-3. If White had made the best play last turn then that would have been correct and 8-6 would have been a huge blunder. Clearly the five blots should have been marked with a "More Is Possible" flag (see earlier post!) and the prospect of 7 blots after, say, 5-1 (23/17*) for White should have any predator licking his lips. Here I was more sheep than wolf, but it's a wake up call. If you play me next week I might have sharper teeth! Until the next time, enjoy the game!

Sunday, 3 October 2010

More Blitz Stuff

In my last post I concentrated on checker play in the face of a blitz, but I also remarked on the correct cube action and said "Note that White should double any play and Red should take, even if he has made the weaker move". Here's the position again. It's 0-0 to three.

It's fairly easy to see that this is a strong double but a lot of players would pass this, so what makes it a take? Assessing game winning chances and gammon losses in blitz positions is very very hard. There is no magic formula that combines all the features of the position in a way that can be converted into maths, so in the end it comes down to instinct. However, instinct can be informed, so what do we need to look at here? From Red's point of view, he won't be on the bar after the play and although he has yet to make a point, all his checkers are in play and reasonably well placed to make points soon. He is only 5 pips behind in the race after the roll. Looking at White's position, we can see that 6-5-4 block of course and the strength of that can't be overstated. It's immense, but looking at the rest of White's checkers it is actually all that she has got! As noted in the last post, she has the stack on the mid and a slotblot in the outfield and watch out for this, it's a very weak formation. You usually can't help getting into it, but once you have it needs to be repaired and soon. Also, crucially perhaps, White has yet to move her back men. If her back men were split, or if her outfield checkers were less fragile, then the take would be very tight and it would probably be a pass for Red if he made any but the best play from the bar.
So, that would be my instinct and Snowie analysis backs it up. Not a pleasant take, but correct, even at 3-away, 3-away, where we need to be more conservative than usual with our takes.
Doubling blitz positions is a lot of fun for the doubler of course. They are very volatile and in one sequence the defender's game can collapse into a gammonish heap. The play is usually a matter of bashing anything you can see and going for a closeout, with the difficult play only coming after you have had one or two checkers hit. One thing I have noticed though, is that several successful blitzes leads to over confidence and the cube in subsequent games gets earlier and earlier! Here's a good example of one.

Red (me) is on roll and the score is 1-1 in a five point match. I doubled this, what would you have done? White incidentally is a Fibs GammonBot, so Red isn't entitled to add any vig for the chances of an incorrect pass. Mind you, a pass would be fairly horrid here, as the double is a blunder. Let's take a closer look to see why.
Apart from the White checker on the bar, her position is actually a bit better than Red's, with the 11pt made and only two checkers back. The race is even. So, Red is doubling on threats and against a human opponent that might be reasonable. We all get a bit nervous off roll with a checker on the roof and I have seen positions like this passed before now. The trouble is that Red doesn't have checkers in position to be very threatening. What this position lacks is volatility. Red has quite a strong game that should develop nicely over the next few rolls, but he is unlikely to make the sort of great leap forward that will lose his market on the next sequence.
After I doubled and White took, I then rolled 2-2. Having fundamentally failed to understand the position, it's no surprise to see that I then blundered with this excellent roll. Take a moment to choose your play in the position below. The score is 1-1 to five.

I chose 13/11, 8/6, 4/2*(2). This wasn't a careless play, I thought, "Put a second checker on the roof and bring down another builder", which seemed reasonable at the time. However, switching points isn't really viable, because I just don't have the ammo for the blitz. Granted I have brought another checker into the zone, but at the considerable cost of giving up my 4pt. What I really need to do here is import a lot of extra ammo with 13/11(3), 8/6. After that excellent play (and kudos if that is what you selected) then I suddenly have 12 checkers ready to blitz or prime as the dice decide. This is so much more flexible than my play, which comits heavily to the blitz plan. Midpoint fans will hate to see it go, but owning your opponent's bar and your midpoint concentrates too many checkers in one segment to be flexible. One or the other has to go and here it is the midpoint. This is quite typical. Look out for this combination and get ready to dismantle it; the two points don't combine well to cause trouble for the opponent and the checkers on the mid are usually more use somewhere else.
The last thing that needs to be said about this disastrous sequence is that you need to be particularly careful not to give away the cube to a savvy opponent at this score (4-away, 4-away). Your take point on a recube is about 32% cubeless, so any time White gets to be a favourite here a recube is in sight! Didn't know that? Then that alone is enough to make reading this blog worthwhile, so until the next time, enjoy the game!