the dorbel daily

Tuesday, 25 December 2012

Confession Is Good For The Soul

Confession is also good for your error rate. If you play carelessly and just say, "Oh well, nobody was watching" when XG pitilessly exposes your blunders, then there is a very good chance that you'll keep playing carelessly in the future. I can't stress enough how important to get into the habit of always trying to find the best play, even in matches against bots that mean nothing. All of us I think, make more blunders through carelessness than we do through misreading a position.
So, for a while, I'm going to use this column to just show you some of the blunders that I make. This will do wonders for my own play and with any luck, the positions will throw up some ideas that will help everybody.

Here's the first of these, dorbel (Black) playing a Fibs GBot (White), both sides 5-away.

I think everybody will make the bar here, so it's a choice of three fives. Actually here is the first hurdle to jump. Did you actively consider all the fives? Can't say that I did, but there's nothing intrinsically wrong with 13/7, just a bit stolid. What I actually did was to make the action play, 23/18, 8/7, but this is easily the worst five. It encourages White to attack while she has the stronger board and no other convincing game plan for the moment. Correct is 8/7, 6/1. Once you've been forced to hit loose on the ace point, it's almost always right to make it, converting a minor embarrassment into a small asset. It's right here, by a lot, as it almost always is in the opening stages of the game. I actually knew this, I just thought that this one might be an exception! It isn't.

Later on I'm on the bar with a 2-1 to play.

 I made the 23pt. I can't really describe this as a thought process, but I think what happened was that my instinct was "Phew, I've entered and I can anchor, so that'll keep the gammons down." That's true as it happens, but of course I have to give up a lot of wins to save those gammons and bar/24, 6/4* is correct, trying to take away half (or all) of White's next roll and stop her adding another point to her prime. Instinct isn't a substitute for thought.

Lastly, if you can stand one more from this terrible game, I hit a late shot and got round to this 5-5.

I took two men off but stacking the ace point and keeping the closed board is right. This makes Black a small favourite, while two men off makes him a small underdog. Once again, thought is required. Taking two men off leaves Black in a seven roll position with a five point board. Playing 11/1, 10/5, 6/1 leaves him in an eight roll position, but White can't enter and from this the worst that can happen is that he will come down to the same thing next turn. If he can throw 3-2, 2-1 or 1-1 he can do better than that, taking off a checker or checkers and keeping the board for yet another roll.

Learn anything? I did, so tomorrow (always a moveable feast on this blog) we'll have a look at some more dorbel blunders.
Until then, enjoy the game!

Wednesday, 14 November 2012

The Big Hammer

The 4 cube is the bg equivalent of the Mighty Hammer of Thor, deadly in the right hands. The player prepared to ship a 4 cube at the first opportunity will wreak havoc at all levels below World Class. The possesion of the cube can be worth a lot, but only if you are prepared to use it! In a recent match I had two opportunities to use it. Here's the first.
You are Black, holding the 2 cube in the first game of a 9 point match. What's the correct cube action for both sides here?

The first question to ask yourself, always, is "If I was White, am I 100% certain that this is a take? If not, it must be a double." This is known as Woolsey's Rule. Pretty clearly you can't be certain that this is a take, with two men on the roof against a four point board, so Black is good enough to redouble. Now move on to question two. "Am I 100% certain that this is too good to double? If yes, play on for the gammon for at least one roll, if no, turn the cube." This is known as dorbel's rule. Purists don't like this rule, but in practical terms it performs quite well.
So, what's the answer? This is a correct redouble and a correct pass, even though Black's checkers are not well placed to close the board and he still has one checker behind a five prime. Failing to cube or taking the cube are both small blunders costing about 1/10th of a point.
Dorbel's rule works quite well in situations where the decision to cube or play on isn't clear, because if you get a pass it puts two concrete points onto the scoresheet and when you get a take in this position , as you often will, you gain 2/10ths of a point in theoretical equity. Actually you often get takes in positions much stronger than this and passes in positions that are much weaker. The point of cubing, often missed, is that it allows your opponent the opportunity to make a mistake. The Mighty Hammer of Four is a terrifying weapon.
 The big temptation is to play on in the hope that if things go well you will win a gammon and if things deteriorate, you'll be able to cash later. That's often the case of course, but it's easy to see here that an "ordinary" number for Black, 5-3 say, followed by the same number for White will leave Black in a position where not only can't he cash, but he won't even have a redouble!
I failed to redouble that one, forgetting my own rule! TIP:More mistakes are made by forgetting the things that you already know than are made from technical ignorance.

Later on I led 4-2 to 9 and holding the cube, got down to this juicy position.

Uneven distribution and different numbers of checkers, so we can't rely on formulae that only count the pips. Black will usually waste a lot of pips here, initially when he throws sixes or fives and later when he gets down to only checkers on the two and one points. White on the other hand will use all her numbers efficiently at first, as even a 3 will fill her gap nicely. She also has two extra checkers off and less wastage on the lowest points. Black though has two things going for him. He gets to roll first and all the lower doublets are much better for him than they are for White. He is a lock to be off in six rolls and to win without doublets White will need to get off in five rolls. She'll have to roll pretty well to do that, so this might be a redouble so I did a Thorp Count . This old fashioned formula is very easy to apply and if you make some little adjustments for gaps, can be very accurate.
Actually here, Thorp rates this as an initial double but not a redouble and given that Black leads in the match he should be a little more conservative than usual in bringing a large cube into play. Nevertheless, making a small adjustment for White's gap makes a difference. Also, Black will get some incorrect passes here and with the end of the match so close, White's opportunities to redouble to 8 are going to be limited, so I finally turned it and White correctly took. Both actions are correct.
Note that Woolsey's Rule still works here. I couldn't be certain that this is a take for White, fairly confident yes, 100% certain, no. If the cube dies with this turn, at 0-0 to 3 say, this position is a marginal take/pass, so a useful reference position.
When you take a 2 cube, part of your equity lies in your willingness to use it if things go your way. Don't be afraid to use it! Swing that Mighty Hammer and reap the rewards.

Friday, 9 November 2012

In The Spotlight Again.

In the previous post, we saw how the bold play was correct, even though it enhanced the match leader's gammon risk. Winning the game is a very good way of not being gammoned! UK expert Rick Janowski points out that in fact in these situations the money play is usually correct and that it is a very common mistake to over-estimate gammon danger for the leader.
Today it was my turn in the spotlight, playing for UK against Moldova in the Inter-Nation Cup on GridGammon. I led throughout the match, so played a number of games where I was keen to keep the opponent's gammon chances down. This one came when I led 8-5 to 11.

I rejected 6/1, 5/1 and I hope that you would too. Burning two spares and leaving the problem of how to  clear the 8pt is not the way to go. Black has to make a bold play while White is on the bar. I went for 8/3, 5/1 leaving five fly shots for White, but this is still not bold enough! The money play, 8/3, 6/2* is best, essential to stop White from making the 23pt anchor next roll. It's so easy when the winning post is in sight to try and avoid the last minute turnaround, particularly when White has such a good board, but it's right to leave eleven shots here and the match play is a smallish error.

Allowing for gammon losses is much more important when the cube comes across. Here's a good example that came when I led 8-2 to 11. White doubles, is this a take?

For money this isn't too hard. Black will at worst have an ace point game to fall back on. This isn't enough for a take on its own of course, but added to his other chances it makes for a pretty easy take. Here though, the cube is worth somewhere between next-to-nothing and not-a-lot and a gammon loss is very serious. XG++ will pass it, as did I , but a rollout indicates that it might be an ultra close take! Good reference position if you save them. Take or pass, this one loses Black one point, always after a pass, on average after a take. If you feel that the position is a marginal take/pass like this, which side should you plump for? Conventional wisdom suggests take, so that your opponent has to play for his point, rather than being handed it on a plate. If you think that you are clearly the better player this makes a lot of sense, as White in this position may well make some mistakes on the way home that will boost your equity a bit. If on the other hand you are the weaker player, it might make sense to bin this one and wait for a better opportunity later. You want to escalate the cube in a relatively skill free environment.
Until it's your turn in the spotlight, enjoy the game!

Thursday, 8 November 2012

In The Spotlight.

Picture the scene. It's an important match, there are watchers and worse still, it's a team event. You are in the spotlight and and you get an ultra tough roll. Even the strongest players can blunder here. Look at the position below. Black, a strong expert, leads 10-8 to 11, post-crawford, after at one stage leading 10-3 Crawford with one point left to clear for victory. All of this adds up to pressure, particularly now he's reached this score and a gammon loss is the match lost.

White is on the bar and Black rolls 5-2. The cube is dead, the gammon threat is one way and the obvious hitting play and the more adventurous double hit are suddenly not so appetizing. What should Black do?
The first plan to abandon is 8/1 to cover the blot and make a three point board. This burns Black's major asset, his broken five prime and it isn't even very safe, leaving 14 indirect shots. It does of course give White nine numbers to dance as well, but she won't be worrying to much about that I think.
Black actually tried 15/8, keeping his prime, adding a builder and cutting the shots down to eleven. He succumbed to the temptation of keeping the anchor as security, because of gammon fear and possibly, the very common failing seen at all levels of not wanting to put the match on the line now.
One of the best ways to avoid the gammon is to win the game! After hitting, Black is the clear favourite (56%) to win the game. After the quiet play he is the clear underdog (40%). He'll lose 23 gammons after the hitting play, but he still loses 15 after playing quietly. It's no contest and 15/8 is a big blunder, cutting his match winning chances by about 4.3%
The best play is 23/18*, 15/13, keeping the shots down to 12 and quite importantly, knocking away White's valuable slot for the bar. It does of course expose Black to the danger of being closed out after a hit, but White doesn't have much in place to go for that after she has two checkers on the bar. Even when she enters those, they are fairly well primed. 
When it's your turn in the spotlight, be brave! Play to win, not to avoid losing. Black here is in a poor psychological state to play aggressively. He had the match all but won half an hour ago and he has been on the defensive ever since as game after game has leaked away. When you find yourself in this sort of position, which you will one day, try to think like a predator, not a prisoner.
Until the next time, enjoy the game!

Wednesday, 31 October 2012

Two On The Bar. Always Better By Far?

Given the chance to put two checkers on the bar, we usually grab it, "Two on the bar, better by far" as my old friend Graeme Sievers, a British Open Champion in the nineties, used to say. Here though is a nice example of when that old saying leads us astray.
It's dmp again, with Black to play 6-6.


After a bit of thought, Black played what might be considered the default play, 8/2*(2), 7/1*(2). How bad can it be to put two on the roof and make a five point board? Here it's a large blunder costing about 0.08 ppg or if you prefer, this cuts Black's game winning chances down from 79% to 75%.
What's wrong with Black's play? The key strategy in one point matches  is to stay pure and this means relying very heavily on primes to win the game and also keeping all your checkers in play and connected.
Connected just means within six pips of each other. In play means not comitting checkers to the lowest points in your board, where they can't be used any more.
You can see here that the blitz play gives up the prime, disconnects the checkers on the far side of the board and buries four checkers deep in Black's board. There's more to this position though, which we can see by looking at White's checkers. She has four checkers balanced on the end of her broken four prime, it is front-loaded. This is a very bad situation for her if she is forced to play next turn, but putting her on the roof means that she won't be forced to crash.
The best play here looks like 24/18, 22/10, 13/7 and 24/18, 22/4 is a fairly close alternate.
What can we learn here? Stay pure in dmp games, priming and connectivity are the key. Particularly here too, look at every checker on the board. It's so easy here to focus on Black's checkers and those blots that White has, but looking at all her checkers quickly shows how fragile her position really is.
It wouldn't be too difficult to edit this position by bringing Black's checkers around until the point where blitzing becomes correct, but I'll leave you to do that for yourself. Why should I do all the work?
Until tomorrow, enjoy the game!

Tuesday, 30 October 2012

The Return of the Dorbel Daily

Well, after a five month break from this blog, I feel suitably refreshed and inspired to re-start it. One of the major problems with the old blog from the reader point of view was that it wasn't in fact daily. I intend to try and rectify that and bring you something each day for us to think about. These will always be drawn from real play and the object is not to find you fascinating, rare and difficult positions, although I hope that there will be some, but to try and build up thought patterns that will help us to deal with the problems that occur a lot. Dealing with a recurring problem that often generates  an error can pay bigger dividends than eliminating a blunder in a position that occurs once in a Blue Moon.
Here's the sort of thing that I mean, an early 6-4 and should I make the 2pt?

It's dmp and White is on the bar. I decided not to make the 2pt and instead played 17/11, 13/9. This creates two new builders for vital points and cuts down White's return shots, a nice pure old-school play. Staying pure at dmp is very important right? However, this turns out on analysis to be the second best play and making the 2pt is best. Can we say why?
The first thing to note is that Black has made the 4pt without using any of the spares on the 6pt. One of the reasons for not making the 2pt early is that our spares are needed for making the more important  5, 4 and 3pts, but once one or more of those are made, we can be much more free and easy with how we use our spares. Also, playing 17/11 leaves the last checker on the ace point rather isolated, with an eleven pip gap to jump in order to rejoin the rest of the force. Note too, that although 17/11, 13/9 cuts return shots from 12 to 6, it also lifts the pressure on White's 11pt blot. Lastly, a point is a point when all is said and done and making another home board point gives White nine numbers to dance next turn, not four! These five extra dances neatly cancel out White's six extra return shots.
Can we do all this thinking over the board? I don't think so. Not only will the game become insufferably slow, but we will quickly exhaust our brains and be in no shape to play well later. What we can do though is to try and do what I have just done here when we do the post-match analysis. Hopefully some of that will get stored in our sub-conscious and reappear in a match when we need it, although we may never see this exact position again of course. However, you may like to try my flag system! This flags particular features of a position with a mental pennant, so that we keep it in mind in our decision making. Stacks with five or more checkers are of course very damaging, the "silent killers" as Robertie calls them, sucking the life out of our position with their inflexibility. Fly a mental flag from the top of your stacks bearing the message "PRIORITY: UNSTACK ME PLEASE". If you still have a stack on the 6pt and you have already made a point inboard, colour the flag fluorescent pink!
I'll have a look at a later position from this game tomorrow. Until then, enjoy the game!

Thursday, 14 June 2012

The End

Apologies to all the readers who have been looking for some content during the last three weeks. What happened? Well, I get a phase now and again when my own play goes completely to pot, as I take huge passes, miss obvious plays and generally play like a clown. This is invariably because I get overloaded, thinking about the game, playing, writing, giving lessons and in the end I just get totally confused! Writing in this mood is quite impossible and as I've had a quiet time on the lesson front, I've taken a break. In the interim, I've lost the match from which I was taking the back game positions, so I can't go on with that either. What is really happening here is that I have to give this blog up for a while, along with playing speed sudoku, Fibs, Gridgammon and watching endless bowling shows on You Tube. I have to get out from in front of this computer and get some fresh air! It's been great fun doing this and thanks a million to those of you who have taken the trouble to contribute. Your interest and appreciation have more than repaid the time I've put into it.
perhaps one day I'll be inspired to kick start it again.
In the meantime, enjoy the game!

Tuesday, 22 May 2012

Back Games, the Myths and the Magic

"Do some articles on back games", is a request that I get more often than any other. It's an odd one in many ways. Back games are rare in modern play, as the first thing we learn about them now is to avoid them if possible! Putting right common mistakes in every day positions pays bigger dividends in the long run. Also, I just don't feel particularly well qualified to talk about a subject that divides players far stronger than me. However, backgames are fascinating, so let's take a look at some  facts and some positions.
What is a backgame? It's a game where one player holds two (or more) points in the opponent's home board and tries to keep them until the bear-in/bear-off stage, in order to disrupt that phase for his opponent, get a shot, hit it and win from there. This player is said to be playing a back game and the opponent is said to be defending against it. In the old days, better players wouldn't mind steering into these, because defending against the back game is very much harder than actually playing one. That ratio of difficulty hasn't changed, but the bots have revealed to us the shocking statistics of how (in)effective the various games are and most importantly how often they get gammoned. Still, the Mad Backgame Geniuses are not completely extinct, although the extent of their success is limited. It's sad in a way, because the games do have a beauty all of their own.
Now I know that as soon as I mention bots, a significant percentage of readers will mutter, "Bots don't understand backgames, so they play them badly". This is not a can of worms I intend to open, because I find discussion of what a bot can and can't do is tedious. Of one thing I am pretty sure though, which is that XG2 plays (and defends) against back games better than 99% of humans! If you disagree, open a thread somewhere else (other blogs are available) and discuss it there please.
There are eight different back games available of which two, the 20pt/24pt and the 20pt/23pt are so weak that they are not playable. The principle strength of back games comes when the two points held are fairly close together, which creates problem rolls for the defender. Points two or three pips apart don't do this. The 21pt/24pt game is also in this category I expect, but is for some reason much rarer and I haven't got any data on that. The 23pt/24pt game is also very weak unless you have enormous timing and the defence against this game is now so well-known and so effective, that getting that timing is almost impossible. I'll try to cover the main points of this game in a later post.
Now you will have seen that I used the T word there, timing. More utter rubbish is talked about timing than almost any other facet of the game, particularly by Mad Backgame Geniuses and I will try to avoid adding my share. Timing means being able to keep your backgame points and the strong prime that you need to win with after a hit, until very late in the game. This doesn't just mean until you first get a shot, it means keeping your position until the second or third opportunity. You can have too much timing and too little and timing is as important, perhaps even more so, for the defender. He should be trying to delay his arrival in the bear-in/bear-off stage if the backgame player is still strong and has lots of timing. The best backgame points appear to be the 22pt/24pt and 22pt/23pt variations. They create the most problems for the defender for sure and we'll look at one of these today.
Here are some positions from a backgame I defended against on GridGammon. The backgame player here has the 23/22pts combo and I have concentrated on the defender's plays.

Position One

Black leads 4-1 to 7 and has 2-1 to play.
Before we discuss the play, we can note that Black has the best anchor and the best board and his only real weakness is the checker on his 4pt, which has no useful function in the foreseeable future and reduces him to 14 playable checkers. White has five checkers back, with the spare ideally placed on the higher of the two points. It's important to note that a backgame doesn't always start at the moment when the two backgame points are made. It's still possible for White to switch out of her backgame and given a good opportunity, she probably should, so Black shouldn't be too adventurous here. The best play is 8/5, not ideal when Black is really looking to prime, but all that he can do for the moment. The more adventurous 13/11, 8/7 is a small error, but close enough to give us a hint of the sort of thing that will be required.
White rolled 3-1 and played 7/3 and then Black has a 6-4 to play.

Position Two

I played 20/10, which I think most of us would play in default of any better plan! It comes out best in the rollout but only by a very thin margin over 20/14, 13/9. Why would that be a good play? When those blots don't get hit, they are in good shape to make Black's 8 or 9pts to extend his prime. When they do Black goes backwards and slows down, improving his timing and thus weakening White's backgame. However, we are now on the cusp of the point at which White finally comits to her backgame, so 20/10 is probably minutely better.
One of the drawbacks to using my own games as examples is that occasionally you get to see a very horrible play. Here's one. I lead 4-1 to 7 remember.

Position Three

Black on roll. Cube action? For money I would say that this is a thin but reasonable double. White does have two very strong points but it isn't at all clear that she is going to be able to time this. She can take quite easily though, because of the two Black spares on the 5 and 4pts that are more or less out of play, so Black can't realistically hope to make any more prime points. At this match score, doubling is a huge blunder. White can redouble on almost any pretext, pushing Black into overage, killing his gammons, killing the cube and activating White's gammons as match winners. This is an X-rated blunder, not to be shown to children and those of a nervous disposition. Note too that White's play is going to be a lot easier than Black's, usually true for backgame players, so she will probably get closer to the theoretical equity than Black.
 White took and then I rolled 5-4.

Position Four

How would you tackle this one? While you are thinking about that, I'll go and get on with some other stuff, so come back tomorrow and we'll see what happened next.
Until then,  enjoy the game!

Friday, 11 May 2012

The Major Split, Right Or Wrong?

Two interesting comments on my last post. In the first Boop commented that it should be possible to program the bot to assess the opponent's playing strength on what it observes in the match and adjust it's cube action accordingly. I expect that this is possible, although my knowledge of computer programming is on the level of an amoeba, but whether it is desirable or not is another matter. At present, when a bot analyses a position, it makes an objective assessment based on the assumption that its opponent is a player of equal strength. If you make it play according to the strength of its opponent, then those who want to learn from the bots will see it making plays that may be optimal to deal with a beginner opponent, but not actually the best play otherwise. In my view it's better to let the bots do what they do and make our own adjustments based on a known bench mark.
David Levy also raises the point that I failed to mention market losers. If your opponent opens with a 3-1 he argues, it is correct to double but equally correct to refrain from doubling. This is absolutely true. If you are strong enough to recognise when you have any market losers (one sequence is enough), then I agree that not doubling may be right. If you are not confident whether or not you have any market losers or even what a market loser is, then turn the cube and concentrate on the game! You cannot make a mistake on your first turn, but you can on your second and subsequent turns. If you don't know exactly what you are doing, why risk it?
This post was written in reponse to several fibsters who queried why a bot would want to double on the first turn in a 2 point match. David is probably in the top 1% of players in the world. You can see why he thought it inadequate!

I have an American student who is a model of how to study. Here is an example and here is the position.
Position A

Black trails 4-away, 3-away and has 6-3 to play. He chose 24/18, 8/5 which is a blunder, costing about 0.11ppg. The best play is clear, 13/10, 11/5 and I commented (with hindsight),  "The 18pt is a bad place to be hit when the 5pt is slotted. Note too that the match play, as well as leaving three blots, rather leaves the checker on the 11pt with nothing useful to do at the moment, whereas the XG play leaves active builders on the 10 and 8pts, very useful."
All very well and true as far as it goes, but then Ace Student reminded me of a position from a previous match. Here it is.
Position B

 Now it's 5-away, 5-away and Black has to play 6-2 from the bar. Here he played bar/23, 13/7, a play which I critiqued as follows.
"I view this type of position with your forces in the role of defenders in a castle. Your play has your forces staying within the walls and declining contact in the hope that things will get better later. Sometimes they do, but more often those checkers get primed and you get doubled out in a roll or two. The XG play forces contact now with a bold sally out through the main gate, in the hopes of exchanging hits and/or making the high anchor that will keep you in the game. As so often, this bold approach pays."
You can see the problem here. In the first position, it's very wrong to make the major split, but here it's very wrong not to do so. He asked, "Why in one case it is correct to split to the 18pt and in another it is not?
The reason 'bad place to be hit when 5pt is slotted' can be applied in both cases."
I expect you want to know why too!
The bar is a bad place to be hit in both positions. The point is that in Position A it isn't a risk worth taking. Black only has two men back and he can play all of the roll very productively on his side of the board, making the 5pt and putting his checkers in excellent shape to build a prime. Also, White's back checkers haven't moved. In (pos B) it is still a bad place to be hit, but now it is a risk worth taking, one that is almost forced on Black. He starts on the bar with three men back, whereas White has partially escaped one man. On his own side of the board Black hasn't yet made a point inboard and his checkers are very awkwardly placed to build a prime. All this means that staying back with three checkers deep in White's board is not feasible and Black has to fight for life now or face being doubled out in a turn or two. Either way he is a clear underdog, but definitely worse off if he doesn't split to the bar.
In position A there just aren't these imperatives to split. Both sides have two men back and Black has a small race lead. He is a small favourite in the game. A nice quiet play is fine.
Splitting to the opponent's bar, whether the 5pt is slotted or not, always has dangers. We just have to weigh risk against gain and treat each occasion on its merits, because there are no hard and fast rules and there can't be in a game where the position of all 30 checkers has a bearing. We do have a tendency to just focus on the point in question, White's bar point in this case and to look at the extra hit and cover numbers, but every piece has a part to play. If you haven't looked at all 30 checkers, you run the risk of making a big mistake.
We can't learn backgammon by learning moves, we have to learn to think about the game while it unfolds. This is a paraphrase of something that Emanuel Lasker said about chess and if anybody knows the original quote, send it to me please!
Until the next time, enjoy the game!

Monday, 7 May 2012

The Great Two Point Match Mystery

I'm going to write all that I know about two point matches, but first, let me direct you to the comment on my last post from Timothy Chow. Timothy adds considerably to my theme and also alerts us to an unusual play of 6-5 in this position.

The "automatic" play here is 24/13, adding an awkward sixth checker to the midpoint and making no positional gain in a race where we trail by 6 pips. However the best play for match or money is the more adventurous 13/7, 13/8, unstacking the midpoint, putting two more checkers into the zone and bidding for a prime. A story goes with this, as I actually found this one for myself several years ago and eagerly looked for a chance to play it. I have seen it exactly twice since, once when I was at GammonSave where it is a small mistake and boring old 24/13 is a bit better and once at DMP where it doesn't matter much what you play!

Anyway, on to Two Point Matches and cube action. A fibster writes, "In a Seven Point match against a bot, we got to 5-5 and the bot doubled immediately and then rolled 5 doublets! Suspicious eh?" Well no actually.
At this score, it is technically correct to double at the first legal opportunity. Even if your opponent starts with a 3-1 which leaves you as a clear underdog, you should turn the cube, so obviously it is correct in every situation. Your opponent will always have a correct take.
To understand this, we need to understand why we don't double this early at other scores. It's because owning the cube has value and the longer the game has until the end, the more value it has. Once you have the cube, you only need to become a strong favourite (about 82%, less with some gammon chances) and you can cash the game. Your opponent by contrast has to get all the way to 100% to get his points. Owning the cube effectively shortens the ladder that you need to climb for victory. At 2-away, 2-away, owning the cube has no value whatsoever, so you can double anything where you have the advantage. "Aha", I hear you cry, "but if my opponent starts by making his 5pt, I am an underdog, so why double?" Because even if you roll your worst, probably 2-1, he should double next turn and you will still have a trivially easy take. This game is going to be played for two points whatever, so it may as well be you who doubles!
There is however one key word in all the above and that is "technically". Technically assumes equal players and correct cube action on following turns. In real life, a strong player playing a much weaker opponent may well leave the cube in the middle, in the hope that by doubling later he may get an incorrect take or pass from his weaker opponent and/or be able to play on for an undoubled gammon. To do this you need to be strong enough to be very confident that you will assess the cube correctly later and you need a considerable skill advantage over your opponent. If everything in this post is old hat for you and your opponent is about 250 rating points weaker than you, waiting to double might be your best option. If you are any other sort of player and/or your opponent is stronger than you, cube immediately.
So, was the GBot correct to double at this score? One weakness that Bots have is that they are not capable of assessing their opponent's playing strength and adjusting their cube action accordingly.  The GBot assumed that it's opponent was equally strong and on his turn would make the best play. A real life player of that ability would probably have played on and gained by doing so.
I write this in the hope that it will be understood and all the players who don't auto double on the first turn will begin to do so and thus win a little more often and thus have more fun, but they won't! There is a huge resistance to making a play that means that the match will end this game. That inertia is hard to overcome, so I guarantee that some of you will read this, even understand and agree with it and still when it comes down to it, not do it the next time they are at 2-away, 2-away! It's your life, live as you want to live!
Until the next time, enjoy the game!

Thursday, 3 May 2012


One of the hardest problems that we face in the early part of the game is when and how to split our back checkers. For a variety of reasons we do have to get them moving. They are vulnerable to being primed where they are and while they are static back on the ace point, our opponents can bring down builders from the midpoint without much danger. Once you have split them, your chances of improving your anchor get better and your coverage of the outfield doubles. The downside of splitting is that you are vulnerable to being attacked, but as you can't win the game without moving them, they do have to get off the ace at some point. It's my belief that for most of us, the time to split is on the first roll, when the danger of being attacked is at its lowest and our opponent is keen to bring down builders to make points. Generally speaking, the computer rollouts support this tactic at level scores and the balance tips even more in favour of splitting when you lead, less so when you trail.
Splitting does have one major benefit for most of us though, which is that in my view, it leads to games that are slightly easier to play where we will make fewer mistakes. The more skilful players, experts and above, like to make the more complex plays, slotting their 5pt aggressively and bringing down builders rather than splitting. For them, this is a good tactic, making the game harder to play so that they have more chance of outplaying their opponent. For the very great majority who will never reach this level and don't particularly aspire to do so, the split play will pay dividends.

It's the Crawford game and Black trails 0-4. White is the stronger player of the two. Black chose 13/10, 13/11. This is, according to the rollouts a minute mistake, 0.004ppg less than optimal so just about as unimportant as it can be. However he should split, partly because it's minutely better, but mostly because it makes the game easier to play. There's no cube in this game, so the back checkers have to move to win the point and the decision of when and how to split them is only going to get harder as the game goes on. 24/21, 13/11 is the usual split with this roll but 24/22, 13/10 is almost as good with the same equity as the two-down play. Worth a try on novelty value!
On his second turn, Black already had a tough choice.

He chose 11/9, 10/9, a 0.060 error. He can either make the 9pt without splitting, or he can make the 10pt and split. As the 10 and the 9pts are roughly equal in value, it's clear that he should make the 10pt and split.
The next turn, the play gets harder still, after White has rolled 5-5, played 13/3(2).

Black played this 24/21, 13/11, on the face of it an entirely reasonable play, looking to make progress on both sides of the board. This is another error though, about 0.068 this time and he should play 13/10, 6/4. Not many people will find this play OTB. As a rule, we are all (often wrongly) hesitant to slot after the opening roll and it's actually quite rare to slot the 4pt with the 5pt empty and it's also rare to want to slot when our opponent has a better board. What makes it right here? The secret lies in the stacks that both players have on their 6pts. These need to be developed and soon and for White it is even more urgent than for Black, as she has no other active builders. Doublets aside, she isn't going to have much chance of converting her stack into a prime, so she will welcome the chance to attack on her 4pt. Splitting also turns her 5-5 on the next turn from a disaster into an excellent roll and the huge swing on this one roll is quite important. Black's stack also has to be developed and the 6/4 slot is a nice way to do it, giving him good sixes next turn too. This play is more attractive here than usual, as Black can't lose a gammon, but it still looks right even at normal scores.
One useful tool for me is the use of mental flags, highlighting features of the board that are important on the next turn. I like to put a flag on stacks. The flag on my own stacks says "Unstack me now". The flag on my opponent's stack says, "Danger of falling checkers, keep clear". Try this one yourself, it's often a useful tool, steering us in the direction of a correct play.

So to recap, split early. It only gets harder later!

Until the next post, enjoy the game!

Monday, 30 April 2012

Five Positions, Answers.

I hope you read the last post, if you didn't go there now! Where have you been? For the rest of us here are the answers to the quiz. Every position has the same answer. These are all No Double and of course Take. In real play, by strong players they were all doubled and passed, which shows the size of reward a dangerous looking cube can reap. Well done Timothy, the only reader who felt confident enough to have a go at these, shame on the rest of you.
Position One.

Score, 0-0 to 5. Blue on roll. Cube action?
Not a bad double this one, Blue wins about 69% here but doesn't have many market losers and actually gives up 0.063ppg by cubing.  However he netted a massive 0.349 blunder when White passed!

Position Two

 Blue leads 3-0 to 9. White is on the bar. Cube action.
This one has very similar equity to Position One.  Blue is about a 76% favourite to win this and can normally recube and expect a take. At this score though, White's potential to ship a very nasty 8 cube means that Blue should wait and that he gives up 0.085 by doubling. White's pass is a huge 0.315 blunder. Blue should wait a turn and double if White dances, usually losing his market by a bit.

Position Three.

Black leads 2-0 to 7. Cube action?
A double here is only a minute mistake, as with about 74% wins, Black is very close to being in the window. White's huge race lead, the absence of builders in Black's prime and the value of owning the cube when you trail in the match all add up to a very easy take and White's pass cost her 0.228. 

Position Four

Score 2-2 to 9. Black has two men on the bar. Cube action?
Black here is a Giant 32 player and couldn't resist doubling here even though he had two men on the bar.  That's a blunder but White folded this highly unusual position, costing himself 0.545.

Position Five

Black leads 2-1 to 7. Cube action?
And finally, Black (me!) should wait here and the cube is a very small mistake, only about 0.024. Followers of this blog know that almost good enough is good enough for me and it reaped a fine harvest when White limply folded, a 0.465 blunder.

Passes of this magnitude do happen, even up to championship level, particularly with some gammon threat and particularly when they are recubes, so be brave. Most of us don't like to pump the cube up against weaker opposition, but as they must by definition be even more prone to this sort of bad drop, perhaps we should be just as aggressive with them too.

The Fibsleague play-offs are posted, and BushSucks (Germany) takes on paulc (USA), while Backwoods is paired with runnerup (Germany). These 11 pointers should be good value, so look out for them on Fibs.

David Escoffery's Spring Open rolls on and dlevy (USA) is the first into the money round of 8. David is an expert on the great games writer Edmund Hoyle and you can enjoy his highly specialised blog here.

Tomorrow I want to say some things about splitting the back checkers, how, when and why! Enough for a whole book there, so I'll only be looking at some general points, but if it's an area that worries you, take a look.
Until then, enjoy the game!

Friday, 27 April 2012

Five Position Cube Quiz

Continuing with the theme of useful tools, I keep a collection of positions sorted by type. You might like to do this too if you find it useful. Today I have a little selection of positions that I have saved grouped together, although the connection isn't immediately obvious.

Position One.

Score, 0-0 to 5. Blue on roll. Cube action?

Position Two

 Blue leads 3-0 to 9. White is on the bar. Cube action.

Position Three.

Black leads 2-0 to 7. Cube action?

Position Four

Score 2-2 to 9. Black has two men on the bar. Cube action?

Position Five

Black leads 2-1 to 7. Cube action?

All the players in the matches where I saw these are strong, expert or world class level. They didn't play these well, can you do better? If you get them all right you will see what links them.
Oh yes, which style of board do you prefer?

I'll come back to these very soon, so post some answers in the comments please!
Until the next time, enjoy the game!

Tuesday, 24 April 2012

In The Tool Box.

Robert Fontaine made some interesting points in a comment attached to my last post. Broadly speaking, he feels that because we make mistakes in so many different areas of the game, trying to work on them all at once isn't going to get results and that we would be better off concentrating on one area and strengthening our technique there. I can see the sense in this, so this is why as a preliminary I want you to find out what those areas might be. First concentrate on blunders, bad plays that have cost you at least a tenth of a point. Keeping these off the scoresheet will imediately move you into the world class category. Then begin to sort these into categories, grouping similar mistakes together. Categories with very large numbers of members are obviously those that are most going to reward work. How you then tackle these is up to you, but we'll look at some methods in a future post.
However, it is my contention that most mistakes are made for non-technical reasons. Mistakes where we have failed to grasp technique are hard to deal with, but mistakes in preparation, attitude and application are not. What do I mean by this? Here's an example.

White leads 2-0 to 7 and has the cube. My student Black played 7/4, 7/1, 3/off. Why did he make this play? "I was going for the gammon" he said. Quite right too, obviously a gammon is just what the doctor ordered when you trail and you've cubed, but there is of course more than one way to skin a cat.
Technically speaking, this play carries some risk, blotting next turn on 6-6, 5-5 and 6-4. Is this a risk worth taking in order to get a checker off? Three factors need to be taken into account. First, White has a nice board already, only three points but the best three and it will improve too. It is always going to be a problem for Black if White can hit something. Secondly, we can see that as it stands, White already needs 67 pips to save the gammon, just over 8 rolls, so if Black just makes the safer play of 7/4(2), 6/3(2) and gets down to an 8 roll position himself we can guess that about half of Black's wins will be gammons anyway. Thirdly, we have to consider extended jeopardy, i.e. what happens down the line. Obviously clearing the 6pt now is going to lead to a much safer and faster bear-off later and this is actually the most important of these three factors. Both plays win about the same number of gammons, actually 47, but the safer play now with less extended jeopardy wins a lot more games, 90 against 82 for the match play. If the race to save the gammon was closer or White's board weaker, or both, then Black's play could be right of course, but here it is a big blunder.
That's the technique and this can be learned and it should, but Black is actually a good enough player to avoid this large blunder in the first place, so why did he make it?
First, he was "playing a quick match while I drunk my coffee before I went out for my run". This is a recipe for disaster. There are no "quick" 7 pointers and you can't hope to play well if you think that there are. Moreover, this sort of casual rushed match breeds bad habits like a swamp breeds mosquitoes.
Second, he played it much too fast. He has a tendency, a very common one, to speed up in the bear-in and bear-off phase, almost like a runner approaching the winning post. Really strong players actually slow down in this phase, because with the winning post in sight, they don't want to trip over their shoelaces! A mistake earlier in the game can be put right, but here it can be disastrous.
Thirdly, this is a doublet and all doublets carry an enhanced risk of blundering, so he should have said "Doublet!" and let go of the mouse. Breathe. Think. This one simple tip will save you lots of blunders, believe me.
Lastly, I am willing to bet that he had the radio on and not made any preparation to play at all. Can you imagine Andy Murray going to play or even train without preparation? Of course not, so before you play, check this list.
 Have I got time for the match and am I in the right frame of mind to concentrate?
Am I hungry or thirsty?
Do I need a pee?
Is my desk tidy? (yes really).
Radio off? Phone on message?
OK, then sit down to play and give it the same effort that you would if it's a tournament for money and the opponent is Kazaross or Falafel (other opponents are available).
What's interesting about the mistake above is not that this is an especially difficult position technically, but that with proper preparation, attitude and application, it wouldn't have been made in the first place. These are things that we can all put right, without so much as opening a book. Try it, you'll play better overnight.

Of course many of us like to play for fun, without worrying too much about mistakes and improving. That's fine, live as you want to live. You'll get no criticism from me, but let me just say that playing better has two advantages. It wins more, always more fun and more subtly, it makes the game more interesting!

Until the next time, enjoy this wonderful game.

Friday, 20 April 2012


A long gap between the last post and this I know. I've been away and then doing some work on my own game and then some thinking about what (and who) this blog is for and then some idle procrastination.
All of us ask ourselves the same question, "How can I play better?" Then we log on and play some matches and then we analyse them and look at our mistakes. Then we play some more matches and so on. At least this way we don't get any worse and over a long period it will help us improve, but noticeably, not by much. After the first year or two, it's rare to make much progress. It looks as if this process doesn't work and I think that is because it isn't sufficiently focussed on the repeating mistakes. So, I am trying a new method on my own game and perhaps this would work for you too.
The method works like this. Go through your match, with Gnu or Snowie or ideally XG2, note the big mistakes and focus on those where you haven't understood what you should be doing and why. Ignore those where where you've had a good idea of what you should be doing, seen all the candidates and made an honest but understandable mistake. With the rest, try to put them into a category by type.A quick list might look like this.
Failed to be guided by the pipcount.
Played a doublet too quickly.
Rejected hitting loose on a low point (always a problem for me!).
Missed a cube by failing to use PRAT.
Failed to stay pure in a crunch situation.
Took a gammonish cube without being certain that it was right.

These are just some of my weak points, your list might look completely different.

Once you have your list and it begins to fill up with repeat offences, you need to figure out why you are making these mistakes. Not concentrating enough? Playing when you are tired (or hungry, or thirsty, or intoxicated, or bored, or depressed)? Not really understanding the position? These are just some suggestions, your own list might look completely different.
To recap, you need to know what sort of mistakes you are making regularly, then identify why you made them and then learn how to avoid them.
Here's an example. A student of mine faced this roll. What's your choice?

It's 0-0 to 5. Make your play before you read on.

He played 13/8, 6/3. It looks fairly natural, but it's an auto pilot play, of the type that we all make when we are feeling lazy. It's a particularly bad time to blunder because this game is arriving at the Crunch Point, where the game will be decided one way or the other. Either Black will get home safely or he'll leave a shot and be hit.
The best play by a lot is 13/10, 6/1. A highly skilled player with a very advanced positional sense might get this right by thinking, "It can't be right to pile a sixth checker on the 3pt. I may very well want to hit something in the bear in, so I'd better slot the ace and then one of the spares on the 3pt will at least have something useful to do." A more pragmatic player or even the same player might think, "I'll make the safest play for next turn, it's usually a good guide." Then he'll read the numbers. This just means looking at all his next rolls after each of the candidate plays (there are only two) and seeing which of them leaves a shot. Did you do this before choosing your play. If you didn't, go to the back of the class! Do it now and you will quickly see that 13/8, 6/3 has 14 blotting numbers next generating a total of 234 hits, while 13/10, 6/1 has only 9 which generate 126 shots. One of these, 5-5, you'll leave voluntary double shots although you could play safe but with much greater extended jeopardy.
So here is a bearing-in error, made by failing to read the numbers. How often do you read the numbers? If the answer is never, then it's time to learn and the only way to do that is to practise, by looking through your matches for bear-in positions and counting them up. Do it with pencil and paper at first, then graduate to doing it in your head. Do it until it is easy and then do it in matches until it becomes second nature to always do it. It's going to swing a lot of losses into the win column. Note that in most cases (and particularly here) you'll need to multiply the shot numbers with the number of shots that they leave to get the definitive answer.

News. Fibsleague season 56 ends on the 27th of April. Master A is still very open with a lot of matches undecided and a lot of players in with a chance of catching current leader BluNick (Italy) who has 8-3 with a match to play. Master B is however decided, with Backwoods (Finland) and BushSucks (Germany) through to the play-offs yet again, so congratulations to these perennial strong men. At the other end, jackdaddy and blotsalot (both USA) are relegated with magic_one, DeaDice (both USA) and Gammonrider (Germany) battling to avoid joining them in Gold next session. This is a very good time to register for the league and enjoy regular tough matches in a well run league, for which we have to thank Franck del Rio, better known as Tomawaky, who is now in his eleventh year as director. Take a bow Franck!

Tomorrow we'll look at another blunder and how it might have been avoided. Until then, enjoy the game!

Tuesday, 3 April 2012

News, Blunders and Answers

So, the answers to my April Fool's Day Quiz. Five positions and no, it's not a joke, I really did blunder all of these in a single match. Nothing like public confession for keeping you on the straight and narrow in the future. Here they are again.

Position One

Score 0-0 to 7

If you were too lazy to do the pipcount, you'll struggle with this one. Black trails by a pip (82-81) after the roll, so mandatory to continue to block sixes. I had no excuse as pipcount was on when I played it, so this has to go down in the "Sloppy and Careless work, see me" column. The best play is the simple 7/5, 4/1 but the imaginative 7/5, 6/3 isn't far behind. The 3pt could yet be very useful and White won't be hitting unless she can roll 1-1 or 1-6. Yes, hitting with 1-5 is wrong.

Position Two

Score Black leads 4-1 to 7

By far the toughest position in this quiz, the rollout is quite clear and Black must play 18/9! 9/4, 7/3, which is what I played is too feeble. If White is going to escape with a five or six, Black must simultaneously slow himself down by allowing the hit. Plays like 18/13, 18/14 also do this, but five blots is a bit too loose, boosting White's wins and gammons by significant amounts. Positions like this lie well beyond my powers of analysis, but it is a very instructive position to practise. Play from here, try some different plays, analyse, get a feel for it. At least you don't have to worry about the cube play. Hard to see Black ever turning it here.

Position Three

Later the same game.

We've had a careless blunder, inexcusable and a very tough play blunder so far. Here I made a "Too clever by half" blunder, opting for bar/21, 3/1*. My thinking was that if I could knock White off the ace point and make it later, it would make the bearin and bearoff much safer. This is true as far as it goes, but I can always take that risk later if I have to. Now is not the time, as two men back could be very dangerous. Big blunder, good old bar/19 is correct.

Position Four

Black leads 6-1 crawford.

I played 10/5, 8/5, another blunder like the last, imaginative but too much risk for the gain. It may have been sparked by the "I've seen something like this recently where it was right" syndrome, to which I am particularly prone. I don't mind that too much actually, as it often pays off, but be wary of relying on it. Use it as an option if you really can't choose something better.
13/10, 13/8 is quite a decent play but a very small error. Black needs to hit something and you can choose between hitting one or two! 10/7*/2* and 13/8, 10/7* are neck and neck in the rollout. I am always very reluctant to start speculative attacks in cubeless games where I can't win a gammon, but here it works just a little better than the quiet play.

Position Five

Black leads 6-3 to 7, post crawford.

Lastly, one from the "Too ambitious" school of blunder. I played 12/11, 7/4*, but the quiet 12/8 is better in the circumstances. My play wins the most games for me, but White's deadly gammons jump from about 20 to 29, so clearly I shouldn't be risking that. Sometimes backgammon is just about cutting your losses and living to fight another day.
Thanks to Julia, Clem and boop for having a crack at these. You can see their ideas in the comments to the previous post. Join them next time, the more the merrier.

Lots of action already in the Spring Open, particularly for sita (Matthias Krings) and yes (Thomas Brizendine) who are off to a flyer with wins that take them into the third round. You can follow this tournament direct on .

We'll have some more dorbelblundas to look at tomorrow or thereabouts, so I look forward to seeing you again. Bring peanuts. Until then, enjoy the game!

Sunday, 1 April 2012

News and Blunders.

As of today, those who base their plays on XG2 rollouts will be looking with interest at new results showing that making the 5pt may not be the best opening 3-1 after all. At GammonGo the wide-open 6/5. 6/3 is almost certainly better, many more gammons and a chance to go into a deep backgame if hit. I look forward to trying it out, so let me know how you get on with it.

The Fibs Spring Open is under way with an entry of 105 players, generating a prize pool of $4, 725.
There are 13 previous winners in the field so it should be a tough tournament to win. This tournament offers a rare Fibs chance to see Kit Woolsey in action, still one of the strongest players in the world.
In the real world, Easter is always the time for the Nordic Open and as usual a very strong field will be on its way to Denmark. It's not too late to book in, has all the details.
A lot of the players from the Nordic will then head off to Velden in Austria for backgammon by the lake on the following weekend. This too will be well run and offer a good deal to players of all standards, so go to for details. Even if you don't think of yourself as a strong player, you'll find a division suitable for you at either of these venues and you'll make new friends and have a great time for sure.

Robert Fontaine recently made the point that it is very difficult to improve one's standard of play, even with a lot of study and work. I know how he feels! There's no doubt though that concentrating on the blunders, the really big mistakes is the way to go. A blunder costs you more than a tenth of a point, so keeping these off your scorecard will make you an overnight expert. Here are some of mine, without comment, so take a look at these and let's see if you would make the same mistakes. I'm playing a 7 pointer with The_Blade, a very strong Israeli player.


0-0 to 7, White has the cube, Black to play 3-2.

Position Two

Black leads 4-1 and has the cube and has to play 5-4.

Position Three

Same game, Black leads 4-1 to 7, holds the cube, is on the bar and has a 4-2 to play.

Position Four

Now it's Crawford, Black leads 6-1 and has to play a 5-3.

Position Five

Lastly, post-crawford, Black lead 6-3, has the cube and has a 3-1 to play.
How hard are these? I got them all badly wrong, so let's see if you can do better. Until then, enjoy the game!

Saturday, 31 March 2012

Midgame Recubes part 2

In the last post we were looking at a five point match. White leads 1-0 and holds the cube and things have gone her way. There's a very strong resistance to recubing anything that has a strong gammon chance at this score for obvious reasons. Here's White on roll in the position immediately following the last position in the last post. Black is on the bar but has managed to grab the 20pt anchor.

Position One

White was too good last turn but with Black having anchored on the 20pt, she can't be too good now. Is she good enough to redouble? It's close, but XG says that she should. How might we arrive at that decision OTB? It's very tough. To me, just looking at it as it stands, it doesn't "look" like a cube. Black will certainly have a game if he can enter somewhere soon, but he can also enter awkwardly. White can lose her market when Black dances again and when she can make the ace point on Black's head. Can't blame anybody for not redoubling this one though.

Position Two

White didn't double and Black danced. Now the redouble is very clear, almost too good in fact. White should redouble and Black should pass, as he has dipped below 25%. He will have a game of some sort if he can enter quickly, but when he can't, his blot on the 24pt is very vulnerable, particularly to doubles that usefully switch points. Again White chooses to roll, a reasonable decision if a small mistake.

Position Three.

Black has entered on the 24pt and been forced off his 20pt. Although White can now attack him there and will, even if she has to hit loose, this isn't technically good enough for a redouble that puts the match on the line. However, it's very close to being a redouble and a 7% chance of a wrong pass is enough to make it correct? There must be that surely? White should recube and give Black the headache. It can't be stressed too often. Look at it from the opponent's point of view. Does Black really want to take this one on for the match? The bot says that he should, but players aren't bots and will be thinking things like "3-0 down isn't so bad" rather than the more useful "have I got 25%?"
Again White didn't double and rolled 3-1, played 10/6. Black rolled 5-1 and made a fatal error, playing 14/13, 6/1. Suddenly White has one more spare and Black has one less. He should have played the brave 14/8, duplicating fives and keeping his checkers in play. That leaves this last position.

Position Four

White hardly had a recube at all last turn, now she is too good again! A recube is a large error and Black mustn't be given the chance to pass. I'd really like to know whether White took these four decisions by assessing them well, or whether she just thought, "Haven't a clue, let's roll and see what happens next"! I think all of these are too tough to assess with a sufficient degree of accuracy to make a guaranteed correct decision. If I was White in these positions, given Black's strong board, I'd have been doubling to see whether he was prepared to play one of these for the match. As I said at the start, cube holders 4-away are very reluctant to redouble and in my experience the player 5-away is very reluctant to take, so it's a bit of a stand-off!
I would recommend playing Position One here for practice after doubling. If you can get this one right and redouble, you'll be spared all the other decisions! Let me know if you managed the theoretical equity of 71-72%.
Until the next time, enjoy the game!

Monday, 26 March 2012

More Midgame Cubes and Recubes

For the player trailing in a short match, his cube strategy can be summed up in the immortal words of Uncle Jake (Jacobs), "Develop an enhanced gammon threat and ship it in". Not very difficult, certainly a lot easier than entering the murky world of gammon prices and match equities at this stage. It is an infallible guide, in which the worst that you can do is give the cube away a bit early. It is worth expanding slightly on what constitutes an "enhanced gammon threat" though. At the start of any game you have about a 13% chance of a gammon if the game is played to the end, so around 20% gammons can be considered "enhanced". However, we can face some difficult decisions, notably when we have thrown a joker and suddenly jumped from not good enough into the "Am I too good?" area.

Position One

Black trails 0-1 to 5 and has just thrown 6-6 to hit three checkers and make his 2pt. White has fanned. Too good to double? Over the board I felt that this was much too good, after all, isn't it a bit wimpy to cash when your opponent has three men on the roof? A rollout suggests though that Black has the same equity whether he doubles or not, 1.00pt. Note that as advertised here ad nauseam, the cash is a real point, the play-on is theoretical and you have to play to get it. This is actually a reference position, although probably too rare to be of much use.
I rolled and covered the 4pt and White entered a man.

Position Two

This is now clearly too good. Black has improved his board and White's entering checker isn't enough to balance that. Everybody plays on, nobody takes, but note that Black's equity after rolling is still only about 1.1ppg. What happened next?

Postion Three

Black hit loose and White entered with a hit to leave this position. In the previous two positions it's been in my mind that even if White enters with a hit, I'll still be able to double from the bar and here it is, Black cubes. This is a big pass. Positions where you have a four point board and a man on the bar and another blot to shoot at are almost always passes. Here White still has two on the bar! Nevertheless, it's bonanza time for Black and White took, a double blunder and Black's equity jumps to around 1.2ppg.
The game took some wild turns from here as White entered everything with a 3-3, followed swiftly by a 4-4 to build a board and here is White on roll considering a recube. Remember she leads 1-0 to 5.

Position Four

Recubes are very tricky indeed for the leader. If she doubles and gets a take, she'll be redoubled for the match with gammons not counting, so the great majority of White players holding the cube at this score are reluctant to turn it, yet another reason to give it to them in the first place!
Black can take with better than 25% winning chances as his equity at needs 5, needs 2 is 25.64%.
Here, he is just a little short of that, but White wins around 37% gammons from here, so by a small margin it is technically correct for her to play on. Her match equity is about 75.5% if she doesn't double and the same if she doubles and gets a take. If Black passes that drops to 74.64%.
Phew! Is there any way to sort all that out over the board? Not for me there isn't. I would play on here thinking myself too good and you can arrive at this correct decison just by fudging it if you say "No idea what's right so I'll take a roll!" However, once again, turning the cube is a good practical move. You score two points if you get a cash for which you pay a small premium and when Black makes a small error, your ME reverts to what it would be if you hadn't doubled!
Whatever you ultimately decide, you must get into the habit of allocating a lot of time to positions like the above. Run through a mental list of rolls, decide how you play them, put them into groups. In this position, I don't ultimately think that it is going to help you decide what you should be doing, because the differences between right and wrong are so small and the complexities are so large, but there will be positions where the process of "reading the numbers" makes your cube action very clear. If you haven't practised it a lot, with positions like this you aren't going to be able to do it in a match.
In live play you have to do this in your head and you are supposed to do this online as well, although I suspect that pencil and paper is sometimes called into play. This is actually cheating, but it isn't cheating to practise like that. Practise playing this one too, it's very instructive!
I'll bring you a bit more from this game in the next post.

BushSucks won the Fibsleague season 55 play-off for a record equalling fifth title, defeating your correspondent in a 2 hour battle over 13 points, so back to the drawing board for me. Until the next time, enjoy the game!