the dorbel daily

Wednesday 26 October 2011

Three On The Ace

The least useful place to have a spare is on your anchor and as the 24pt is the weakest anchor, it follows that having three checkers on it is very bad. It's practically an invitation to the cube, so should Black, who is on the bar double this? If Black doubles, should White take? It's the first game of a five point match and Black did double this and White (dorbel) passed. Give it some thought and then read on.

If you thought that Black is actually too good to double then I would say that that is a reasonable view, given that White already has three back and three more blots are waiting to be hoovered up. OTB I thought that might just be the case and so passed very quickly. To my surprise, this is a correct take. What is happening here? To find that out, you have to revert to the only technique that we had before bots, the hand rollout. In the old days, this involved hours, sometimes days, of playing the position over and over again, ideally with a friend, often alone! There were some techniques for reducing the dice variation, notably changing the opening roll each time, but the number of games that you could complete and the inevitable playing errors made the results of little value in determining the most likely outcome. However, it did give you some practice and a little confidence when you met something like it in the future. We can still do this now, but using the "Play from here" feature on the bot. It will set the pieces up, play one side and tell you afterwards how you played too, allowing you to improve your play in the position as you go on. You can swap sides.
I did this with this position and discovered several things. The first is that because of his awkward position, Black's play is far from straightforward, so in order to achieve anything close to the bot cubeful equity of around 0.9 he will have to play brilliantly. The second is that the position White fears, where she finds herself in an ace point game with several checkers behind a prime just doesn't happen! When she isn't hit, her blots become slots and builders. When she has one or two checkers sent back, she still has lots of play because Black only has a two point board and can't develop it quickly because of his awkward position. All this is not to say that Black is not hot in this game, he will win about 62% from here including 33 gammons, but White does have a take and must seize the chance to play a long difficult game owning the cube. This is particularly true at this score, where the recube can come earlier than usual.

As so often happens, I quickly saw something very like it again.

Also in the first game of a five pointer, but as you can see with several features that improve Black's game. He isn't on the bar and White is, one of his back men has escaped and his forward checkers, although still stacked, are a bit better placed for an attack. I would have passed this, correctly, but Black decided to play on for the gammon. It's quite a reasonable view to take, as he can usually cash later if he wants to, but double/pass is correct. I always repeat a little mantra here, culled from early reading. I think it's Robertie. "The side playing on for an undoubled gammon against an ace point game is either making a mistake or has already made one". This is a very valuable piece of information, although there are scores where playing on is clearly correct, usually when an undoubled gammon wins the game for you.
At the risk of repeating myself to my regular readers (Sid and Doris Bonkers of Neasden), my philosophy is to only play on for the gammon when I am certain that it is correct. When it's a close decision but playing on is correct, this sometimes costs me a small piece of theoretical equity, but it does put a real point onto the scoresheet without having to play to get it. Also, the icing on the cake, sometimes they take!

So, the next time you see a position and you ask yourself, "What is going on here?", play it. You'll learn a lot more from it than you will reading books, or indeed this column.
Until the next time, enjoy the game!

Mochizuki Masayuki v. Matvey Natanzon, a 13pt IIBGF Match.
Mochizuki Masayuki v. Carlo Melzi, a 13pt IIBGF Match.
The XG files for these matches, annotated by me and approved by Mochy are now available, $10 each. Gnu and Snowie users can have a Gnu file with the commentary on a separate word doc. Both matches show brilliant play at the highest level and are very instructive for students at all levels.
PayPal please and enquiries to dorbel(at)gmail(dot)com.

Monday 24 October 2011

Three Puzzle Answers

Well done to the panel of three bold enough to give us their thoughts on the positions in the last post. The question as to when it is right to slot your own bar is often difficult and I find that it is much influenced by recent events. If I analyse a match where slotting the bar is right and I have missed it, I'm on the lookout for it in the next match and then slot when I shouldn't!

This was our first position, but it came in the next match after I had seen positions two and three, so I was unduly influenced in favour of boldly slotting the bar and leaving 25 shots. 13/9, only 17 shots is a lot better. 6/2 only leaves 16 shots but that checker isn't very useful. Note that the checker on the 9pt is either a slot for that point or a builder, very useful.

Position Two gave us three 4s to play after entering. 8/4(2) is pretty clear and the last 4 is 11/7, giving a double shot, but it's a good point to fight for and it does duplicate 4s and 2s on the other side. It does leave 21 shots though and so I went for the miserable 6/2 which only leaves 17. This dumping play is often wrong, but right just often enough to make it an attractive play when we have been hit a lot in the recent past! Again note the bar point's dual slot/builder function.

Position Three again had Black to enter from the bar and seeing that Black was in the lead, I decided to race it, bar/23, 21/15. This is actually much the hardest of the three positions, so you won't be surprised to hear that I got this one wrong too. 13/7 is easily the best play, unstacking the midpoint and slotting a very valuable point. It is counter-intuitive to risk another man back when you lead in the race, but this bold play has several things going for it. Again, it is a dual slot/builder whereas the 15 pt is neither. It unstacks the midpoint and in doing so applies some pressure on White to tidy up her three blots. Handily it duplicates fours as well.

Not perhaps the world's most exciting positions, but our panel only scored 6/9 so not so easy either. The lesson is to clear your mind of past history, the last match, the last game, even the last move, because past short term experience is a poor guide. A clear mind is a better environment to find the right answer than a cluttered roomful of unwanted baggage.

I've got a student match to look at now and no doubt that will throw up something interesting for us to look at. It's a rare match that doesn't. Until later then, enjoy the game!

Friday 21 October 2011

Three Puzzles

There's a great temptation when writing about bg to highlight extremely rare positions where the right play is an elegant and counter-intuitive gem. As the chances of ever seeing anything like it again are vanishingly small, we don't add much to our store of knowledge, although I suppose anything that leads to our viewing backgammon as a never-ending series of puzzles is a good thing. Here's three fairly ordinary looking positions. How would you approach these? They are all from a five point match. In the first it's no score and Black has to play a 4-3.

In Position 2, Black leads 3-away, 5-away and has to play 4-4 from the bar.

Finally, same score and Black is on the bar again with a 6-2 to play.

There's no particular trick to these, but they do have a common theme. Well they have two things in common actually, I butchered all of these as Black!

Let me have your thoughts please and I'll discuss them in full in the next post.

Mochizuki Masayuki v. Matvey Natanzon, a 13pt IIBGF Match.
Mochizuki Masayuki v. Carlo Melzi, a 13pt IIBGF Match.
The XG files for these matches, annotated by me and approved by Mochy are now available, $10 each. Gnu and Snowie users can have a Gnu file with the commentary on a separate word doc. Both matches show brilliant play at the highest level and are very instructive for students at all levels.
PayPal please and enquiries to dorbel(at)gmail(dot)com.

Until tomorrow, enjoy the game!

Monday 17 October 2011

More Answers For The Famous Five

These are the rest of the answers to the Famous Five Quiz. If you haven't seen that, go back two posts.
Here's Position 3. It's a money game and White has the cube, Black to play 2-1.

I really like this one, because it illustrates a point that many players overlook. All our panel went for 24/22, 14/12*. Alertly they had all spotted that this gives Black sixes and fours to escape, as well as several combinations of numbers to make the bar point. To be honest, I might have made this play too, but it is in fact an error, costing 0.05. Why so? Because it ignores the fact that before we can carry out our threats to escape or make a five prime, White gets a turn. The panel's play works brilliantly when she dances, but when she enters she has 21 numbers to hit Black off the 3pt. Her board is as strong as ours and she has an anchor, we don’t. When that works for her, our blots in the outfield are a liability, not an asset. When we stay back and button up in the outfield with 14/12*/11, she doesn’t have any of these options. With some numbers (64, 44, 42, 41 probably) she will hit us off the 2pt, but that is in any case less dangerous than being hit on the 3pt.
This is not by any means a typical position. The diversification that seduced the panel is a good basis for attacking any problem. It doesn't arrive at the right answer here, but we all might have got it if we had taken the trouble to think about what White's roll might contain.
Oh yes, how does making the five prime look? It looks like a double whopper with fries. Life threatening.

Then we come to position 4, with Black to play 3-1. Black must hit of course and look around for a three. Actually I say "of course", but one of the panel chose 8/5, 8/7. This blunder won't do. Black can't really hope to keep White at bay with that weedy 14pt anchor, although he will have a take when White doubles.
How did the rest do?

Two of them chose 14/13*, 8/5, nicely diversifying the 8pt stack. This leaves 19 return shots at three blots, 3 of which double hit. Our fourth panelist chose 14/13*, 4/1, keeping the shots down to 16 with only one double hit. This is of course good, but the ace point is just not where you want your blot to be. Both these plays are blunders. White should double from the bar and Black will have an unpleasant take. Our last man standing went for 14/13*/10, alertly giving himself sixes as another cover for the 4pt. Again though, just like position 2, White gets to play first and this play gives up 19 shots, including three double hits. Actually it's five, but White won't double hit with 4-2. This play is much better than the rest, except for the best play of all, which is 14/13*, 14/11. 17 shots and two double hits and this combination is the winner. After any play White should double and Black will have a take, fairly easy after a good play and unpleasantly close to a pass after a bad one.

Position 5, with Black to play a 6-4.

One panellist opted for the "safe this turn" play 8/2, 6/2. It's not a bad play, but it burns two of Black's three spares in order to make a weak point behind the anchor and leaves Black with TMP, Too Many Points. Avoid making seven points if you can. It's very inflexible and leaves you with a lot of numbers that leave a shot next turn. Another tried 13/7, 8/4, which got my vote too, pretty positive and with lots of returns if White can hit. However, it doesn't address the main feature of the problem, which is that Black is going to have to leave his anchor in order to get into a doubling position and with this roll he should try it now. He has a small lead after the roll and a better board, but the main argument is that this is just the least bad 6! If he is going to leave shots, it may as well be in pusuit of his main aim, which is escape. One panellist went for the wide-open 22/16, 13/9, but best of all is 22/16, 8/4, the choice of two of our guests.

Many thanks to those brave souls who put their opinions on the line for us, heroes all. Why don't you have a go too, the next time we have a quiz?

Until the next time, enjoy the game!

Saturday 15 October 2011

The Famous Five Find The Answers.

The "Famous Five" were the heroes of a series of British children's books written by Enid Blyton, although I doubt if they are much read today. On their holidays the intrepid and ageless quintet invariably encountered a criminal gang engaged in nefarious nocturnal pursuits and defeated them with skill and derring-do. What Julian, Dick, Ann, George and Timmy the dog would have made of our Croatian Quiz is anybody's guess, but thanks to the Famous Five readers who tackled them on behalf of everybody else.
Before we take another look and reveal the answers can I say that these are really tough problems that might well have beaten anybody, because they are not easily solveable without a lot of thought. Each is in one way or another unusual and not responsive to the "usually I do this" method" that gets us through most situations.
Here's Position One again.

White is "stripped and stacked", a hugely inflexible position to be in. If she can't throw a life-saving double there is going to be a blot somewhere that Black, trailing by 8 pips after the roll, will want to hit. To take advantage of that he needs to cover his blot and over the board I would have tried 13/9, 6/4. This got one vote from the panel and is the third best play. It does beat 22/16 which got two votes, but that play fails on two counts. It doesn't make the four point board and it runs into a race where Black trails. It is a blot that has no useful function when it isn't hit; a blot on the landscape one might say. Another panellist tried 23/21, 13/9, but again, it doesn't make a four point board. It threatens to make it, but that is never as good as actually making it! Lastly we had one vote for 23/21, 8/4, which was also my student's play.
And the right answer is...............22/20, 8/4!
There is an excellent YouTube video where Falafel, Bob Wachtel and Michy discuss a play from Bob's match. Then Bob reveals the right answer as per computer rollout. Falafel says, "Now I know the answer I understand the position", which is very funny and also very wise. So, what is happening here? White's position is the key, because she is really stuck for play with her outfield points all stripped and her 6pt stacked. What XG's play does, after it has crucially made the 4pt board, is to deny White safe landing points. Playing 23/21, 8/4, the second best play although still a large error, allows White to dump checkers onto her 1 and 2pts and even more importantly, denies her the option of playing to the 11pt in relative safety with most twos and fours.

Position Two was a lot easier with only three posible plays.

Bar/20/14 got no votes from the panel, another "blot on the landscape", trying to race into a race where Black trails, although not by much. Bar/20, 24/18 got two votes and is the usual answer to this sort of thing, forcing contact while Black has the better board, in the hope of exchanging hits or making a high anchor. Three of our panellists went for bar/20, 13/7 and that is clearly best. It beautifully illustrates two themes that recur constantly. The first is that Black has killed two checkers on the ace point and fatally wounded two more on the 3pt, which is the casualty list when a 5-5 blitz fails. This means that his remaining 11 checkers all have to work extra hard, doing the work that is usually done by 15 men. In bg terms, this means more risk. In addition, Black still has a stack on his midpoint, 5 out of his 11 playable men in one place. I always put a mental flag on a stack that says "Urgent: please unstack me". It's no use saying, "I can't do that now, I've got other problems". Positional flaws like this have to be dealt with immediately. Again, in the immortal words of Falafel (possibly quoting Italo Calvi), "If not now, when?" The handy duplication of threes makes the medicine go down a little more easily.

I bet you can't wait for the other answers, but you will have to wait until tomorrow, as I have a flat to tidy before mrs dorbel comes back from her holidays.

Mochizuki Masayuki v. Matvey Natanzon, a 13pt IIBGF Match.
Mochizuki Masayuki v. Carlo Melzi, a 13pt IIBGF Match.

The XG files for these matches, annotated by me and approved by Mochy are now available, $10 each. Gnu and Snowie users can have a Gnu file with the commentary on a separate word doc. Both matches show brilliant play at the highest level and are very instructive for students at all levels.

PayPal please and enquiries to dorbel(at)gmail(dot)com.

Until tomorrow, enjoy the game!

Thursday 13 October 2011

The Famous Five

A little Quiz for you today, five puzzling positions from a student in Croatia. All of these are from money play, where as always the Jacoby Rule is in force and there are no scores to alter the value of gammons and the cube, so they should be easy, right? Let's see, in each position Black is on roll.

Position 1

Black to play 4-2. What and why?

Position 2

Black's 5-5 attack in the opening has failed miserably and now he has to play 6-5 from the bar. A choice of three sixes, so which and why?

Position 3

Black has already doubled and now has a nice 2-1 to play. This one will surprise a lot of you I know. What and why?

Position 4

Black to play a 3-1, neither easy nor obvious. What and why please.

Position 5

It has been said that the ability to play a poor roll well is "the calling card of a pro". This is a poor roll, so can you find Black's best play here? What and why please!

If you get all these right for the right reasons, then you should be writing your own blog. I'll be back in a day or two, with some of the thinking which might lead you to the right play if you meet these toughies one dark night.
Until then, enjoy the game!

Wednesday 12 October 2011

Another Dorbelblunder.

We left Black in this position last week, trailing 0-4 to 7 with the cube on White's side and apparently up the creek without a paddle. What is the correct cube action?
This is a handy reference position, easy to remember as White wins 88% of the games and 8 of those are gammons. At this score Black needs about 10% to take and redouble for the match, because that will be his equity if he passes and trails 7-away, Crawford. We can do lots of calculations to see whether White should redouble, but let me simplify it for you. At this score, it's almost impossible for White to have a correct redouble while there is a chance of a gammon.
Even leaving gammons out entirely, White's doubling window is so small, between 87 and 90% roughly, that her chances of ever being in it are minute. She'll either be not good enough, or she'll have a cash. Doubling now kills White's gammons and puts the match on the line, so playing on until those gammon chances have gone and then cashing is always the plan. In real terms, if White redoubles for the match, she'll be 88%. If she plays on and never redoubles she'll be 87.8%, but clearly she can do a lot better than that by using the cube to cash in all the games where her gammon chances disappear and retaining her 65% match equity in the horror games where she loses.
Player skills come into this. If Black is a world class player playing an intermediate, he should probably pass this, as his theoretical ME of 10% going into the Crawford game will be a lot better than that, because he will outplay White, which he can't really do if he takes this. From this it follows that intermediate White should turn the cube.
However, doubling does have one big plus for White. Humans hate to take and put the match on the line, so if White redoubles here, she will get a lot of wrong passes, from those who underestimate Black's winning chances and from those who know that the take is theoretically correct, but would rather try to win from 7-away, Crawford. In this match White (eberlein a very strong player) doubled and Black (me) feebly passed!
Doh! Tomorrow, if it ever comes, I have some lovely quiz positions for you, all of which were sent to me from Croatia. I forecast that this country has a very bright BG future, with a lot of good players improving fast and the Croatian Backgammon Federation - Hrvatski backgammon-tavla savez, up and running to promote the game there.
Until then, wherever you are, enjoy the game!