the dorbel daily

Wednesday 27 July 2011

A Reader Writes, Part 3.........

Dear Dorbel, In the position below, I moved 23/14. It looks to me like this only leaves a hit by a 4 or a 65 and if I am missed I should get in easily. However, Gnu thinks that I should play 23/18, 6/2.
It looks as if I leave the checker back on the 18 it will be much more likely to be hit after my next roll, if opponent gets a checker out to my 7, 8 or 9pt. I cant see the advantage of staying back.
Thanks as always,

Position ID: s90AAg73nAcAEA

It's the Crawford game in a five point match and Blue leads 4-0.

Yes I see what you mean.
"Only" a 4 and a 6-5 to hit is a lot of only, 17 shots or 47%. "If missed, should get in easily" is also questionable, as only 10 numbers (28%) get you home next turn. Sometimes it is right to take a direct shot when racing a straggler home, but these usually happen when your opponents home board is weak but about to get stronger, which doesn't apply here. Keeping the shots down with 23/18, 6/2 is clearly best. You may be able to hit something next turn to smooth your way home, or find a relatively safe point to land on. I agree that you may have to face more than 17 shots next turn, but you are just as likely to be facing the same or less or even none at all.
Your play is a small but clear error. If it left fewer shots or got you closer to home, it might be right.

Gnu's 2-ply analysis suggests that the two plays are very close (o.010), but a rollout shows that in fact 23/14 is an error costing 0.032. This translates to 52.4 game wins by staying back and 50.8 by running all the way. Can we draw a golden rule from this that stayng back has to be always best? Not really, reduce the shots and get the straggler closer to home, change the home boards a bit, any of these might make leaving the direct shot better or very close to equal. In the end, it's our old friend "pay now or pay later" and all you can do is add up what you risk and what you stand to gain by giving the shots straight away. If you do that and make a mistake, that's fine. It was probably, as here, a close decision anyway. If you fail to add up the hitting numbers and the number of rolls that get you home safely, then you will be making a guess and serve you right if you get it wrong. These crunch positions demand a lot of thought. Don't shirk it.

Have a look at this close relative to our starter position. How would you play 6-5 here?

Position ID: s90ABA73nAcAEA

Taking the immediate risk with 23/12 is more attractive. It's only 16 shots, but much more importantly, Blue gets a lot closer to home. Now 20 numbers get him to safety next turn and this is just enough to tip the balance and make "pay now" the correct choice. It's very close though, the rollout makes that play best by just 0.009.

Thanks to A. Reader for the position. Until tomorrow, enjoy the game!

Saturday 23 July 2011

WIT FM, the Answers

The commonly held view in backgammon is that the focus should be on checker play, because typically 75-80% of our errors occur in that area. My somewhat maverick view is that in fact concentrating on cube play and getting that right is more important. Why is this? For many years I'd observed that there were players in the chouettes and tournaments who made a lot of obvious errors in checker play, but survived and even prospered in the chouettes and did surprisingly well in the tournaments too. I could also see that there were very skilful players, mostly from the Middle East and the shores of the Mediterranean, who didn't get the results that their excellent checker play merited. It became obvious (to me) that the factor uniting these two groups was their cube play. The first group compensated for their checker weaknesses with a very accurate appreciation of the equity of positions, thus saving them from bad takes and enabling them to make efficient doubles. The second group, who had often been playing from childhood in a home where their father and their uncles took pride in skilful and subtle play, floundered badly with the cube, because it is to this day almost unknown in their home countries.
However, given that our bot analysis demonstrates clearly that most of our error rate is accumulated with the checkers, why does the cube matter so much? It works like this. Each match that we play is of course broken down into individual games. If the "luck" was more or less even in each game, then the most skilful player would win it, but this almost never happens. The usual dice in any individual game give one side or the other such an overwhelming advantage that it can't be overcome by skilful play, even if one side plays world class and the other side plays beginner! The better player's skill is swamped by the dice and the key skill in the great majority of games is to get the cube in the right place and at the right level.
So, does this mean that we need pay no attention to checker play? Not at all. There will occasionally be a game where the dice are even enough for the skill to count, notably the cubeless games as they have to be played to a finish and are thus longer than the others. There is also a great deal of skill in suiting your play to the position of the cube, notably in not overplaying a position and taking a bigger risk than needed in order to ship an efficient cube next turn.
Most of all though, checker play is important because the superior player will get the "luck" in a game more often than not. I had thought this for a long time and spent many hours trying to find the flaw in the argument, until finally a long thread on Fibsboard, illuminated by the contributions of boomslang, pck and Zorba among others demonstrated that this clearly was so and why.
Read it and marvel.

So now, when looking at the games of an individual, I concentrate first of all on their cube action and here are the positions from the last post and what I wrote about them at the time.

Position 1

Black on roll, first game of a 5 point match.
He doubled and I commented, "You doubled this and I can sort of see why. You lead in the race, your position is clearly better (one back against three, stronger board, outfield control) and you do have some threats but I think it is very important to see whether those threats lose your market and by how much. Over the board I would say, “Well if I can jump out and she does nothing special, it might be a pass, maybe not, but I’m not even a favourite to escape. I like to wait and see.” Basically, White is anchored, all her checkers are in play and the situation isn’t very volatile, so trivially easy take. Everybody takes this. The next sequence was Black 4-1, 11/7, 8/7, pretty good and White rolled 5-1, correctly played 24/23, 8/3*, but pretty bad. Now it’s a very strong double, probably a close pass, ideal. You get a point with a pass and probably about 1.07 points with a take. Note though that the point is concrete, on the sheet and you get it without making another play. The 1.07 points is theoretical and you have to play well to get it against an opponent who owns the cube. I would be pleased to get a pass here and wouldn’t mind if I got a take, nice position to be in.

There are two other things that you need to note here. The game has a long way to go if played to a finish, so the cube is completely live, i.e. at its most valuable. Also, you can take a little deeper than usual in the first game of a five pointer, because the redouble is unusually powerful. There are several reasons for this which I am happy to write about if anybody wants to see that, but for now note that the player owning a 2 cube at the start of a five pointer can wreak havoc with an aggressive redouble".

Position 2

Black leads 2-0 and is on the bar. He doubled this and this is what I wrote for him.

"A very early double, a blunder and a very easy take for White. If it was White that led 2-0, this is a double all right, but for the leader it isn't. Why? Once you lead in a short match (or towards the end of a long one), then doubling positions where the threat is largely to win a gammon is counter productive. In this case, if you win a doubled gammon, then one of the extra points for the gammon is wasted. Not only that, but if White redoubles, you don't get anything for a gammon at all and in addition, you can only use use three of the four points on the cube! Lastly, this position is extremely volatile and hard to predict, the opposite of what you need for a double when leading. You want a fairly static position close to White's take point, a holding game or a race ideally, one where the recube isn't going to be scary."

Position 3

Black leads 2-0 to 5 and is on the bar. White is on roll and redoubles.

"Clear redouble for White, killing the cube, nullifying Black's gammons and activating White's gammons as match winners. A huge pass for Black, for all the reasons above. White has a better position and a race lead and attacking threats. For money, easy take for Black with the cube very much alive and fair gammon chances himself, here, get out now and play at 2-2. "

The volume that you need to explain all this is a short volume called "How To Play Tournament Backgammon", by Kit Woolsey and published by Gammon Press. Not a modern volume, but it clearly explains the hows, whys and wherefores of adapting your play to match scores. Essential reading.

That's enough for today. Until the next dorbel daily, enjoy the game!

Friday 22 July 2011

What's In This For Me?

In this post I want to take a look at some positions from a lesson with a fibster. This player, a relative newbie to bg, has a rating around the 1900 mark so clearly can play more than a bit. We're going to take a look at his cube action and today we'll just have a look at three positions from a five point match and see how you cope with them as a quiz.

Position 1

Position ID: 4LsHACawzyMDCA

0-0 to 5. Black is on roll. What's the correct cube action for both sides?

Position 2

Position ID: kevBARTg28EYQA

Black leads 2-0 to 5. He is on the bar and on roll. Cube action for both sides?

Position 3

Position ID: 4NuJAUgx14MBFA
Black leads 2-0 to 5

Black is on the bar and White is on roll and owns a 2 cube. What is the correct cube action for both sides?

There you go. Favour us with your answers and much more importantly, your reasoning please.
I'll be back soon with the answers so don't delay!
Until then, enjoy the game!

Wednesday 20 July 2011

Which Point Should I Clear?

I promised you some cube positions from a private lesson today, but I just want to polish those a bit before putting them in the window, so here's a nice position from a Dutch reader. It's a money game, how should Black play 5-4?

Actually, the first thing to note about this position is that for money, Black should have doubled before this roll and presumably for several rolls before that, because money games are invariably played with the Jacoby rule, which states that you can't win a gammon unless there has been a cube turn. This is a huge pass, so Double/Drop. What about for match play? Curiously this is a very valuable match play reference position, where Black's equity is 1 point whether he cashes now or plays on for a gammon. As doubling secures the point for certain and playing on is worth a theoretical point that will require some skill to acquire, then to me, doubling is clearly correct. Worth remembering this one.
Now to the play. Lucas, playing Black here argues strongly for 7/3, 7/2. His reasoning is that he doesn't want to clear the 7pt later against direct contact with the anchor. If he plays 8/3, 8/4 he can see that 6-5, 6-4 and 6-3 next turn will leave a direct shot and that even if that is missed he has lots of bad sixes next turn as well. It's worthwhile to quantify the immediate risk to start with. 6/36 shot numbers multiplied by 11/36 hits equals 66/1296, a 5% chance of being hit in other words. Obviously playing 7/2, 7/3 reduces this "next turn" risk even further, but it does bury two checkers deep in the board, increasing the likelihood of leaving shots later when Black has to clear his stripped high points. In other words, clearing the 7pt first is less immediate risk and more later risk and as it happens, the two balance out almost exactly! It doesn't really matter which you play.

A subsidiary question. If Black plays 8/3, 8/4 and then on his next turn leaves a shot on the bar which White hits, can White double (or redouble) while she still has a checker behind Black's five prime? It depends on how much time White has left in which to throw the escaping 6.

It might look like this, if Black cleared the 8pt, White threw 6-4, Black left a shot and got hit with another 6-4. This is exactly a marginal take/pass so more timing for White, Black should pass, less timing and Black can eke out a take. It's much the same for a recube if White owns it. I assume the start of a longish match, but of course scores may radically affect either decision. Again, an excellent reference position to remember. If your brain works in that way, you might like to collect these two and start a collection for revision sessions.
Nice position, thanks Lucas. I quite like this close focus on a single position, rather than looking at three or four at once. Is this better for you too? Let me know, feedback is always appreciated, even if negative.
Until tomorrow, always a notional concept in this blog, enjoy the game!

Tuesday 19 July 2011

Answers and More Questions.

Position ID: 4PPgAWAzTvABMA

Here's Position One again. Black isn't too good to double because he doesn't have enough men in the zone to threaten a quick closeout. He must double now though, to avoid a joker sequence and this is a big pass for White. Playing on for a gammon is an error, if an understandable one, but taking is awful, a double blunder. If you voted to take this, then I suggest that you play it out 100 times with the cube on your side and disabuse yourself of the notion for ever. White will win this about 31% of the time, but lose about 40% gammons.

Position ID: 4HPkQUAzTvABMA

Here's Position 2, same sort of thing but now only one checker on the roof. This one is also double and pass. Again Black is momentarily short of builders, but more are arriving on the next bus and White gets gammoned too often to take. Periodically, there is a movement to claim this as a take, indeed some people do take it in practice, as does Gnu 2-ply, but it's wrong in my opinion, based on several long rollouts. Compared to Position One, White wins this one about 33% and loses about 39% gammons.
In both of these I attached a score of 0-0 to 9, but note that when trailing in a longish match these can quickly become viable takes for White. If she can make a high anchor in the next couple of moves, an aggressive redouble to 4 can net a surprising number of gammons of her own. Even in a five pointer, you can take position one quite easily if you trail 2-0. Not only does Black waste one of the two extra points that he wins with a gammon, but White's aggressive redouble eliminates all Black's gammons and even wastes one of the points for his plain win.
Those of you who like to research these things might like to make a little table of correct cube actions after an early 5-5/dance sequence. I could do it for you, but you won't remember it. Do it yourself though and you just might.

Position ID: 4HPwCSCwZ/ABMA

Now here's position 3, with Black on roll at the famous 4-away, 2-away score. You can double almost anything with a sniff of gammon at this score, because it kills the cube and the gammon threat is one way. So, this is a double and it is takeable. So close is this to a pass though, that the slightly inferior White play of 24/18, 13/10 with her opening 6-3 is a pass. How important is that? Not very. You'll probably meet this exact scenario five times in 25 years of bg and making the correct decision gains you at most an extra 0.2% match winning chances when it does occur each time.

Position 4 was the same position as above with Black trailing 2-away, 1-away Post Crawford. Black should play on for a gammon for the moment, but remain alert to doubling. If his gammon chances drop a lot and/or White gets to a position where she might become favourite, double/pass will be correct. For example, if from here Black rolls 3-3 and plays 13/10*(2), 6/3(2) and White then rolls 4-3 and anchors, then the double is probably correct. If White anchors lower down, it's probably right to keep going for the gammon. You can see that the playing on strategy, while clearly correct, does require a lot of good judgment, so if you think that this is beyond you, then taking your point now and going into the last game might be a good idea. It's an error, but not a large one. Too good to double/pass.

In the next post I want to show you some doubling positions from a private lesson. Easily the most common fault among players from novice to advanced is missing doubling opportunities, so I'll show you some of those and what we should be looking for to make the most of chances to up the stakes. That'll be tomorrow with any luck, so check back and until then, enjoy the game!

Saturday 16 July 2011

"A Reader Asks.......Part 2"

As a follow-up to the last post, I now have the whole match from which that position came and here is the same game three rolls earlier. Thank you to Warner Bouzek who sent it to me. Feel free to do the same if you have something interesting.

Position ID: /10AABiz3QYQAg

Here is an excellent opportunity for a trap play. The best play is 20/18, 16/14, 7/3. Note how the moves to 18 and 14 cover every point in the outfield, ensuring a direct shot or its eqivalent after every five or six for White. Even if White rolls 5-1 or 5-2 and picks up her inboard blot, Black will still have 17 shots at the White checker on the deuce point including 6-6 and 4-4 from the 14pt. Even when White rolls 5-5 and covers the blot, Black still has 15 shots from the bar.
Some players will jib at the risk involved, unwilling to let White out in order to pursue a closeout and a gammon. Experts won't, because they have been here before. If you instinctively make the "safe" play here, then you won't know what happens after the trap play and you'll never learn to play it. You can avoid this by playing it fifty times and comparing the results with fifty rounds of your safe play. You'll soon grow to love the trap!

Another reader writes, "How early in the game should I think about doubling?" The answer is that you should always be alert to a double opportunity, as they can occur from the second roll onwards. Here are four examples. Take a look at them and let us know in the comments section what you would do with these. In each case Black is on roll. I want to know the correct cube action for both sides.

Position One

It's a nine point match, the first game and White opened with a 5-2, played 24/22, 13/8 and Black pounded her with 5-5. White danced. Should Black double and if he does, should White take?
Position 2

Again, nine point match, White rolled 6-2 and played 24/18, 13/11 and again, Black rolled 5-5 and again poor old White danced. Should Black double and should White take if he does?

Position 3

This is from a 5 point match and White leads 3-1. Black started with a 3-1 and White rolled a 6-3, correctly played 24/15. Should Black double and should White take if he does?

Position 4

The same position but now White leads 4-3 to 5 and it is post-Crawford. Should Black double and if he does, should White take?

Some of my expert readers will look at these and say, "Well these are too easy". However, they are all from live matches, all involving players at the top of the tree and all drew mistakes from one side or the other! See if you can do better please.

Until tomorrow, which may even be tomorrow, enjoy the game!

Friday 15 July 2011

"A Reader Asks............."

A reader sent me this position from a recent match and asked, "Why does the bot want me to break the bar point here? It thinks I should have broken it on the two preceding rolls as well. Surely I need to keep the last two White checkers contained?

It's 0-0 to 3 and White has the cube in the position below.

Position ID: /x8AABhzux0AAA

In this position it is correct to play 7/3, 7/5(2), getting ready to start the bearoff next turn and allowing White to exit with fives. This is good enough to make Black a 93% favourite in the game and about 7 of those will be match winning gammons. It is often right to keep the prime if White still has a good board and you want to force her to break it with fives, but with this roll you wouldn't do that anyway. You would have to play 7/1, 5/3 leaving you horribly stripped and vulnerable to leaving a shot, perhaps even a double shot.
A third alternative that becomes viable when White's board is fatally crashed, down to 3pts or fewer, is the trap play. Here that would be 7/1, 7/5, deliberately leaving a blot that White will be forced to hit with a five. The idea is that if White does hit, you can recirculate the hit checker, attacking the blot on the 2pt and hoping to close out two checkers for a gammon. It's not right with this roll, because Black's spares are poorly placed, but with a roll of 3-1 for example, it's well worth a try.

Position ID: /x8AABhzux0AAA

After 7/6, 7/4 you can see that if hit, Black will have ones, twos, threes and fours to hit back from the bar, a total of 31 shots. If White can't hit or has to leave with a six, then Black's checkers are ideally placed for an attack or to start the bearoff as the dice dictate. This play will lose at worst 1 game compared to the safe play, but will win about 8 extra gammons, which is good action.
Perhaps this reader was deceived by the pipcount, which shows White leading 59-67 before the roll. This is very misleading, because if it comes to a race, White will waste tons of pips bearing all those checkers off the ace point. A more accurate White pipcount allowing for that wastage would be about 100. How did I do that? You need to use the Effective Pip Count, developed by the late Walter Trice for just this sort of position. I could explain it to you, but if youare interested (and you should be because it is very, very useful) then go to and read it for yourself. Then read it again, however many times it takes to settle into your brain. It's priceless.

Got any positions you want to ask about? I'm easy enough to find on Fibs or GridGammon, or if you like use the comment form at the end of each post and include a Gnu ID. I'll be happy to give you my opinion.
Enjoy the Game!

Wednesday 13 July 2011

Books and Magazines

I am often asked to recommend books. I invariably suggest "Backgammon Boot Camp" by the late Walter Trice. Walter wrote a series of articles for the online magazine GammonVillage under the title Beginner's Boot Camp, taking everybody through the basic techniques in beautifully written, clear and accurate lessons, embracing quite advanced concepts along the way. Even if you feel that anything with beginner in the title is not for you, believe me this book is still essential reading. As far as I am aware, these articles are still on GammonVillage, so you may prefer to buy a Gold subscription and get the lot plus a huge archive of great articles by Jacobs, Zare, Hickey, Sax and others, plus annotated matches, news, terrific value.
Generally speaking, books written thirty or more years ago are only of historical interest, but from that time "Backgammon" by Paul Magriel is still brilliant, although probably worth getting the 2004 reissue. Anything from then by Danny Kleinman is great reading, entertaining and thought provoking, particularly "Vision Laughs At Counting". Bill Robertie is probably the most prolific author, although the quality of his work varies a lot. His "ModernBackgammon" is an excellent work for the advanced player and it includes a 25 point annotated match between Jerry Grandell and Nack Ballard, worth the cover price on its own.
"How to Play Tournament Backgammon" by Kit Woolsey is a fairly short book, but essential if you want to understand how to tailor your play to match scores.
Finally, in this anything but comprehensive list, a cheapy worth ten times its cover price is "100 Backgammon Puzzles" by Paul Lamford. The choice of positions is excellent and from each Paul draws a neat little conclusion that will help you when you meet something similar along the way.

Perhaps the worst ever book is "Backgammon For Blood" by Bruce Becker, a complete guide to playing like a bozo and losing all your money quickly. It was apparently Dubya's favourite and is hilariously entertaing, without meaning to be. Do not confuse this with the book of the same title by Chris Bray, which like all Chris's writing is entertaining and useful. His publisher chose the title without telling him!

All of these are available new and used from various outlets on the net, search around, have fun and build up a little collection. I recently found on ebay a copy of "Complete Backgammon" by Walter L. Richard, 1931, with dustjacket, signed by the author and dedicated to Harold Thorne, also a writer of that period. I hope that you will be as lucky.
Until the next time, enjoy the game!

Monday 11 July 2011

Themed Quiz Answers

Thanks to those who took the trouble to comment, yah boo sucks to all those that didn't. If you are afraid to offer an opinion because it might be wrong and you think that you would look stupid, forget it! An opinion, with some reasoning, even when entirely wrong, is something that we can learn from. On YouTube there is a clip where Michy, Falafel and Bob Wachtel (They don't get much stronger than this) are discussing a position. All of them get it wrong (!!) but it is still fascinating to listen to them.
Join in, don't be scared.

It's the Crawford Game and Blue leads 12-1, so no cube, Blue can't win a gammon, but White can and benefits from it quite a bit because she gets to 10 points away from winning the match, potentially two gammons and a plain game. If she only wins a single this time, she'll need three gammons.
Here's Number One again.

White could delay with 8/7/1 but this turn probably represents her best chance of uniting her stragglers with the rest of her forces. Blue can usually play for two or three more turns before he has to break the midpoint and will probably strengthen his board in the process. If he has to hit now, he still has a lot to do. It's our old friend "Pay now or pay later" and Blue's blot inboard and empty 5pt says pay now. It isn't very easy to jump the big gap between White's stragglers and the Blue midpoint, so she probably will have to do it in two rolls in any case. 16/9 is the play. I could also have just said "What Moonshadow said" as he covered all the bases effectively!

In Position 2, Blue is on roll.

I expect anybody might make the “obvious” play 0f 8/5, 8/2, but clearly best is 23/14(!). What does this achieve? The main point is to free a checker that isn’t doing anything useful. It isn’t making life difficult for White on the 23pt, in fact it is more of a target than anything. If Blue can get this checker into the game, he stands a reasonable chance of building and preserving a board that can win the game if he hits a shot. It has several other things in its favour too. It generates a double shot after 4-4, 3-1, 2-2, 2-1 and 1-1 on White’s next turn. It prevents White from making his 5pt next turn with 3-2 and 4-1, as he will have to hit. It creates the possibility that White will make a large error and choose to make the 5pt instead of hitting. It also creates an awkward 6-5, as White will have to hit and slot a point, thus leaving direct shots. All of this adds up to pressure. Even when hit, Blue will hardly be worse off than he is now and will have gained 11 pips of timing, more if he dances! 13/7, 8/5 is if anything worse than 8/5, 8/2 as it fails to make a four point board.

This liberation of the odd checker from the back is the theme of this quiz and we see it again in Position 3.

Blue should avoid the obvious trap of making the 20pt, as he will generate a lot more shots by staying back now that White is ready for the bearin. However he does need to play 23/20 with the 3, ready to escape if White doesn’t make the point. As on the previous turn, Blue loses little by being hit, gains timing if he is and increases his chance of freeing a valuable checker if he isn’t. 13/11, 13/10 is a close alternate, a small mistake, but making the 20pt would be a blunder.

Lastly Position 4.

The essential part of this play is 23/22. Failing to pick up the 23pt blot loses double the number of gammons. All the plays have White winning 82% of the games here, but 23/22 keeps the gammons down to 6, all the other plays lose 12. These extra gammons come about in two ways. The first is when White points on the blot and Blue dances for a while. The second is when Blue is forced later to play a 6 from the 22pt and gets attacked and closed out.

Sensing when a blot behind the anchor is an asset and when it has become a liability is a key skill, because it comes up so often. There is no short cut, you need to think in concrete numbers. In Position 4, the only roll I can see that generates a shot for Blue is 6-5 and even that is a very mixed blessing because White will just point on the deuce point. Then Blue might dance, useless, or enter on the 22pt, reasonable but he could have moved there anyway, or 11/36 hit. Even the hit is of very questionable value as Blue will still have three checkers behind a 6 prime and most of the time White will just dance until Blue crashes.

Well, I learned a lot from close study of these positions and if you did too, that's a bonus.

I'll be back tomorrow(ish) with some more nice positions from which we can draw a lesson. Until then, enjoy the game!

Friday 8 July 2011

The Themed Quiz. Part One.

I promised you some positions from Mochy v. Melzi, an IIBGF match that I am annotating at present. Four of them, all from the same game.
Blue (Melzi) leads 12-1 to 13 and it's the Crawford game.

White (Mochy) is on roll here and has a 6-1 to play.

Diagram 1

Position ID: 2szgABaYuxswAA

In the next position (diagram 2), Blue is on roll and has a 6-3 to play.

Diagram 2

Position ID: mLs7IADazOAAFg

In diagram 3, Blue is on roll and has a 3-2 to play.

Diagram 3

Position ID: mLt3AAC2NeAAFg

And finally, in diagram 4, Blue to play a 6-1.

Diagram 4

Position ID: se1uAAC2bYQAFg

Do not assume that because this is a quiz, the "obvious" answer can't be right. Stay objective! Make the play that you would make over the board, in a match, although here of course you have the luxury of taking your time. You can even, recommended, set out the pieces on your board and shuffle them around a bit. I'd be pleased to hear your answers in the comments section and your reasoning is much more interesting (to me) than what you decide to play and whether you get it right or wrong. The whole point of this blog is for you and me to learn and the key to improving is to establish a method of looking at a position that gives us a chance to find the answer. The answer itself is much less important than how we arrive at it, because one thing is for sure, you will never see any of these positions again!
Answers please! Until we meet again, enjoy the game!

Monday 4 July 2011

Champagne Answers

So let's see some answers to our mini-quiz.
Here's the first one, 0-0 to 13, Blue on roll.

Blue is too good to double, although not by a huge margin and of course White should pass. Blue will have to constantly re-evaluate this and usually ends up doubling later. One of the nice things about using a bot (in this case Gnu) to rollout a position, is that it can tell you how many wrong takes you would need in order to make the double correct. Here, the figure is about 15%. As I can't imagine anybody taking this, playing on has to be correct.

Here is Blue re-evaluating two turns later.

Pretty clear that Blue still has a strong double, but is he too good? By the narrowest of margins, an infinitesimal 0.015ppg, he is too good, so this is a nice reference position, one where you can't really make a mistake. If I find myself uncertain whether I am too good to double or not, then I always turn the cube. If it's a small mistake, as here for example, then it does at least put a point on the scoresheet. To me it has to be worth paying a small price to score a concrete point that I don't need to play for. Moreover, sometimes they take and then of course you are very happy! Gnu kindly points out that a 3% chance of a wrong take makes the double correct, so if you can imagine that there is a 1 in 33 chance of a take, then cubing is right. The last factor that you have to consider in these "Moet or Veuve" moments is, "How good is my opponent?" Actually, the White checkers here are being played by a World Champion, so nailing the point has to be correct I think. Against a very weak player, I don't know. Playing on allows for the possibility that he will make lots of weak checker players, but doubling allows him to make a huge blunder right now! It's your call really.

Now for the really tough one.

Blue doubled this one from the bar, correctly as it turns out. He is just inside the doubling window and can lose his market with a good sequence. It's very important to remember that market losers are a sequence of rolls, one for either side and also important to be clear that that sequence doesn't have to be very dramatic. In this position just anchoring can be a winner for Blue if White doesn't answer with a very good roll.
This one really divided a very knowledgeable gallery, with a surprising (to me) number going for double/pass, but the take is very clear. Not only is Blue on the bar, but he hasn't yet made his crucial 4pt and if the worst comes to the worst, White is at least anchored, so will be in the game right to the end if he wants. Excellent double though; over the board I wouldn't have doubled if I had got to this position, which I wouldn't have done because I would already have cashed and be playing game two!

I'll try and find you some more positions from this match, as I am currently working through a full annotation of it. Until tomorrow (possibly) enjoy the game!

Sunday 3 July 2011

Moet or Veuve?

One of the most pleasant decisions that we face comes when we have to decide between playing on for the gammon or doubling and taking a point. This is rather like the man in the Marbella supermarket (true story this), who I heard call out to his wife, "They 'aint got no Moet luv, you want Veuve?" Here are three positions from a Gridgammon match. It's the first game of a 13 pointer and the Blue checkers are being played by the expert Italian Carlo Melzi. Take a look at these and decide what is the correct cube action for both sides. You'll do well to get all three right.

Position One. Blue on roll, 0-0 to 13. White is on the bar.

Position Two. Blue on roll. 0-0 to 13.

Position Three. Blue on roll, 0-0 to 13, Blue is on the bar.

Three positions of varying toughness, so take some time and decide what is the correct action for both sides. A large and well informed gallery of watchers got at least one of these wrong. How will you do? The comments section is there, so share your thoughts.
Until tomorrow, enjoy the game!